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Asteroids & The Asteroid Belt

I found this interesting:
Although Vesta and Ceres are tiny compared to Earth, they have a surprisingly large influence on our planet's orbit.

A study published this week says that because of chaotic interactions between Vesta and Ceres, astronomers will never be able to calculate Earth's trajectory more than 60 million years in the future, or rewind it more than 60 million years in the past.

Vesta and Ceres have frequent close passes with each other that change their orbits. The result is that their orbits are chaotic, changing in ways that are impossible to predict more than about 400,000 years into the future.

Gravitational tugs from Vesta and Ceres in turn affect the orbits of Earth and the other planets. The effect of these small tugs build up over time, making it impossible to calculate the positions of the planets more than 60 million years forwards or backwards in time.

Astronomers will more precisely measure the positions of Vesta and Ceres with the Dawn spacecraft, but this will hardly matter for long-term predictions.
The chaotic interactions between Vesta and Ceres will quickly amplify even the tiniest of measurement errors, foiling any attempt to predict planet orbits beyond the 60-million year horizon, says the study's lead author Jacques Laskar of the Observatoire de Paris, France.
"[This] appears to be an absolute limit that will not be improved in the future," he says.

http://www.newscientist.com/article/dn2 ... ystem.html
 
Snowman in space: Nasa's Dawn probe sends home stunning close-up images of crater-covered Vesta asteroid

Since entering orbit last month, Dawn has taken more than 500 images
Vesta's southern section is dominated by a giant crater
The northern side is filled with older craters including three that scientists have dubbed 'Snowman'

Read more: http://www.dailymail.co.uk/sciencetech/ ... z1Tt4iOx00

BIG pics, and a video showing rotation. :D
 
Asteroid could be fledgling planet that never formed
A potato-shaped asteroid observed last year by a European space probe may in fact be the ancient remains of a planet that never formed, astronomers said yesterday.
7:30AM BST 28 Oct 2011

"This is the first object of this kind we have ever seen," said Stephane Erard of the Paris Observatory. "For virtually the first time, we have found a witness to the formation of the planets."

Three studies published in the US journal science reported the outcome of an encounter last year of the asteroid, 21 Lutetia, with Europe's comet-chasing probe, Rosetta.
The scout turned an array of cameras, thermal and spectroscopic sensors on Lutetia as it raced through the asteroid belt between Mars and Jupiter.

Astronomers calculate Lutetia to be 121 kilometres (75 miles) long, 101 kms (63 miles) tall and 75 kilometres (47 miles) wide.
It has a complex surface, pocked by craters in many areas, including one that measures 55 kms (35 miles) across, where the asteroid was hit by smaller objects as well as shafts, crests and escarpments and smooth, younger-looking plains.

Lutetia's high density, at 3,400 kilos per cubic metre (212 pounds per cubic foot), its large size and its ancient surface make it different from any other asteroid studied so far, the studies said.
Mr Erard, in charge of spectroscopic analysis and co-author of one of the papers, said it was likely to be a planetesimal - a fragment of the material that clumped together to make the planets at the birth of the Solar System nearly four billion years ago.
"We believe that Lutetia is not debris resulting from a collision. Instead, it's probably one of the holdouts of the (Solar System's) primitive population."

Planetesimals are defined as rocks that, after clumping together grains of cosmic dust, become big enough to generate a gravitional field of their own.
This attracts other bodies, eventually forming proto-planets, or the planetary embryoes.

Those planetismals which failed to become planets were left to wander in orbit, according to this theory. Over the aeons, they collided and shattered into smaller asteroids, of which there are many millions.
As a result, there are relatively few planetesimals left, distinguished by their great size, said Mr Erard.

Scientists are excited by planetesimals because beneath their radiation-battered exterior could be pristine material that gives clues to how the planets were formed.

http://www.telegraph.co.uk/science/scie ... ormed.html
 
I've beem interested in asteroids since my early teens, space pirates used to hang out on them. At least in SF stories. Maybe we coukd Terraform Vesta.

Giant asteroid Vesta 'resembles planet'
http://www.bbc.co.uk/news/science-environment-17481911
By Paul Rincon
Science editor, BBC News website, The Woodlands, Texas

Dawn's view of the south pole of the giant asteroid Vesta

Related Stories

Asteroid Vesta reveals its scars
Dawn probe orbits asteroid Vesta
Asteroid shaped by great impacts

The giant asteroid Vesta possesses many features usually associated with rocky planets like Earth, according to data from a Nasa probe.

Vesta has been viewed as a massive asteroid, but after studying the surface in detail, scientists are describing it as "transitional".

The Dawn spacecraft has been orbiting Vesta - one of the Solar System's most primitive objects - since July 2011.

They have documented many unexpected features on its battered surface.

Mission scientists presented their latest results at the Lunar and Planetary Science Conference (LPSC) in The Woodlands, Texas.

Dawn's principal investigator, Christopher T Russell, told the meeting that the science team found it hard not to refer to the object as a planet.

He said the rounded asteroid showed evidence of geological processes that characterise rocky worlds like Earth and the Moon.

Getting hammered
Vesta is the second most massive of the asteroids, measuring some 530km (330mi) in diameter. It is dominated by a huge crater called Rheasilvia and bears many other scars left by the hammering it has received at the hands of other asteroid belt denizens.

One important transitional feature of Vesta can be found in its topography, or elevation. Vertical elevation on the Moon or Mars might reach tens of kilometres, but these objects are also very large.

"This means the topography is about 1% of the radius," Dr Ralf Jaumann, from the German Aerospace Center (DLR), told BBC News. If you go to Vesta, it is 15%, and if you go to the largest outer asteroid - Lutetia - it is 40%."

In short, this mathematical relationship between topography and radius (half an object's diameter), puts Vesta in an intermediate position between small asteroids and rocky planets.


Images reveal an interplay between dark and light material on Vesta's surface
Another aspect concerns the way its surface has been modified, or "processed", by the many collisions. This is evident in dark material that can be seen in images of its terrain.

The dark material seems to be related to impacts and their aftermath. Scientists think carbon-rich asteroids could have hit Vesta at speeds low enough to produce some of the smaller deposits without blasting away the surface.

Higher-speed asteroids could also have collided with Vesta's surface and melted the volcanic basaltic crust, darkening existing surface material.

Scientists are confident there has been volcanism on the asteroid during its history. This is because there are hundreds of pieces of Vesta sitting in museums around the world.

They form a particular class of meteorite called the HEDs; more of these objects have fallen to Earth than all the meteorites from the Moon and Mars put together. Studies of HED meteorites have revealed telling chemical signatures of volcanic activity.

Major cover-up
Dave Williams, from Arizona State University, told BBC News: "We know [from the HED meteorites] there were lava flows at some point in history, so I expected there to be at least a few lava flows, maybe a few channels, shields or cones. Looking at all the images in places that have been illuminated thus far, we don't see any evidence of that.

"That's because of all the impact processing over Solar System history. It has destroyed all the evidence."

Mission scientist Brett Denevi, from Johns Hopkins University Applied Physics Laboratory in Maryland, explained why she thought some of the collisions that have hammered Vesta were intense enough to melt its surface.

Referring to observations of a crater called Marcia, in Vesta's northern hemisphere, Dr Denevi commented: "We think what we're seeing here is at least a portion of this target rock has melted and flowed. The impact velocities were high enough - at least in this one case."

She added: "Impact melt hasn't really been observed on asteroids before. It wasn't really expected because the speed of collisions in the asteroid belt are pretty low compared with the inner Solar System. So it wasn't known whether you'd have enough energy to melt the target rock."

Dawn is set to depart Vesta for an even bigger object - the spherical "dwarf planet" Ceres - in August for an arrival in 2015.

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Asteroid Vesta is 'last of a kind' rock
http://www.bbc.co.uk/news/science-environment-18027933
By Jonathan Amos
Science correspondent, BBC News

A computer generated perspective of Rhea Silvia basin, which was dug out by an impact a billion years ago

Related Stories

A fleeting encounter with an 'inbetweener'
Giant asteroid 'resembles planet'
Asteroid shaped by great impacts

Vesta is the only remaining example of the original objects that came together to form the rocky planets, like Earth and Mars, some 4.6 billion years ago.

This assessment is based on data from the Dawn probe which has been orbiting the second largest body in the asteroid belt for the past 10 months.

The findings from the Nasa mission are reported in Science magazine.

They confirm that Vesta has a layered interior with a metal-rich core, just as Earth, Mars, Venus and Mercury do.

Using information about the shape of the asteroid and its gravity field, scientists can even say something about the likely size of this core.

The Dawn team calculates it to be about 220km (135 miles) across, representing about 40% of the radius of Vesta, or roughly 80% of its total mass.


Cutaway model: Data indicates Vesta has an iron core that is about 220km across
"This mission at Vesta has been a spectacular success," said Carol Raymond, Dawn's deputy principal investigator from Nasa's Jet Propulsion Laboratory in Pasadena, California.

"It's transformed Vesta from a fuzzy orb into a planetary body, which has exceeded our expectations in many ways."

Dawn has studied in detail the pattern of minerals exposed in Vesta's surface by innumerable impacts through the eons. It has also mapped the diverse geological features that shape its surface.

These observations have enabled scientists to elucidate a history for the colossal rock, which is second in size only to Ceres in the band of material moving between Mars and Jupiter.

The researchers believe Vesta formed within the first two million years after the first solids came together in the Solar System, before the planets we know today were formed.

Short-lived radioactive materials would have generated enough heat to melt Vesta's insides and produce a subsurface ocean of magma.

This melting would have led to differentiation, to denser materials like iron falling to the asteroid's centre.

Other such bodies in the infant Solar System with magma oceans ended up becoming parts of Earth and the other planets. Somehow, Vesta did not; somehow, it survived obliteration in the cascade of impacts that would have marked those early times. Nothing telescopes see today in the asteroid belt quite matches what Dawn has seen at Vesta, suggesting the mighty rock is unique.

"Vesta is special because it has survived the intense collisional environment of the asteroid belt for billions of years, allowing us to interrogate a key witness to the events at the very beginning of the Solar System," said Dr Raymond.


The crystalline structure in HED meteorites: These common meteorites can now be tied definitively to Vesta
Another in a series of stand-out discoveries about Vesta is the definitive association that can now be made between it and the howardite-eucrite-diogenite, or HED, class of meteorites.

Based on telescopic observations, researchers had always suspected these common meteorites came from Vesta. But the signatures of pyroxene - a mineral rich in iron and magnesium - in those meteorites have now been matched precisely with mineral signatures spied in Vesta's surface by Dawn's instruments.

The HED meteorites account for about 6% of all the meteorites seen falling to Earth.

Common they may be, but their value to science is greatly increased following the Dawn mission because researchers now know they offer some remarkable insights into the earliest epoch of planetary formation.

Much of the HED material is likely to have come from two huge impact basins at Vesta's southern pole.

The Rhea Silvia crater measures some 475km in diameter, and gives Vesta the look of a punctured football in global images.

It overlies the Veneneia basin, which is a little less extensive at 375km across.

"Our estimate [is that] about 250,000 cubic miles [was] excavated from Rhea Silvia," said Dr David O'Brien, from the Planetary Science Institute in Tucson, Arizona.

"To put this into another perspective - 250,000 cubic miles is enough to fill the Grand Canyon a thousand times over."

Some of that excavated material lies just outside Rhea Silvia crater, but a lot of it would have gone into space to form the group of much smaller Vesta-like objects seen in the asteroid belt and, of course, those HED meteorites that have fallen to Earth.

The pattern of craters on Vesta has allowed the Dawn team to age Rhea Silvia and Veneneia. The former was created about a billion years ago; the latter was dug out by an impact around two billion years ago.

The ages are much younger than had previously been supposed.

The other great impact basins in the inner Solar System, such as the ones that pock Earth's Moon, are considerably older, dating to a period about 3.8 billion years ago.

Scientists suspect this period to have been a very dynamic phase in the early evolution of the Solar System and even have a name for it - the "late heavy bombardment".

The ages of Vesta's big impact basins put some new constraints on the timing of that bombardmentand and the region within the inner Solar System affected by it.

Dawn continues to study Vesta. It has an extension on its mission that will allow it to stay at the asteroid until at least 26 August, when it is due to leave on a three-year cruise to Ceres.

The Dawn team is hoping to be able get images of the north pole, which, as a result of the seasonal angle to the Sun, is currently in darkness.

Dr Jim Green, the head of planetary science at Nasa, indicated that the team would be given sufficient time to complete its work.

There is considerable excitement about what might be found at the north pole, with the suspicion being that the terrain may reflect in some way the seismic repercussions from the Rhea Silvia impact at the opposite pole.

"With Dawn's ion engines, which are running much better than predicted, it really enables us to stay at Vesta longer," Dr Green told BBC News.

"We're very excited about that because it will enable us to map the unknown region. That region is very important to look at now that we know about the Rhea Silvia impact basin. How that impact might affect the northern hemisphere will now be revealed."


Crater counting is used to date the surface of asteroid Vesta. Rhea Silvia and Veneneia appear as undulating lines. Note how the terrain of the north pole has yet to be revealed

[email protected]. and follow me on Twitter
 
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That'll make it a useful base when we mine the Asteroid Belt.

Asteroid Vesta's hydrogen suggests water-delivery role
http://www.newscientist.com/article/dn2 ... -role.html
13:50 21 September 2012 by Andrew Fazekas

It's no aqua-world, but the giant asteroid Vesta is surprisingly rich in one watery ingredient – hydrogen. The discovery, combined with its oddly pitted terrain, suggests that water arrived on young planets – including early Earth – during an intense round of meteor impacts.

The 530-kilometre-wide Vesta is unusual among asteroids because it's thought to be the seed of a terrestrial planet that didn't finish forming.

"Vesta is an example of such a world – as Earth once was – frozen in an embryonic state," says Mark Sykes, an astronomer at the Planetary Science Institute (PSI) in Tucson, Arizona, who wasn't involved in the new studies.

The object therefore offers clues to the earliest stages of planet formation in our solar system.

Using data from NASA's Dawn spacecraft, PSI's Thomas Prettyman and colleagues compared the chemical composition of Vesta's surface with that of howardite-eucrite-diogenite, or HED, meteorites.

Dawn's spectral maps show more hydrogen in regolith, near the asteroid's equator, and less in relatively young impact basins, including the large crater Rheasilvia, from which many HED meteorites probably originated.

Hits and pits

"Vesta, like our moon, was thought to be bone dry, and yet we find this material that has been distributed all over Vesta's surface," says Prettyman. The HED meteorites, meanwhile, contain traces of carbon-rich chondrites, some of which hold significant amounts of water-bearing minerals.

The team thinks hydrogen was delivered to Vesta though a swarm of carbonaceous chondrite meteors. These rocks hit at slow enough speeds that their hydrous content was preserved on Vesta's surface. Later, high-speed impacts ejected some of the hydrogen-rich surface material, leaving behind the erratic pattern.

The idea is supported by 30- to 500-metre-wide pits seen in Dawn's images of some smaller craters, according to a second study led by Brett Denevi of the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

Denevi's team thinks the pits formed when some of the impacts caused volatile compounds – also found in carbonaceous chondrites – to degas due to the high temperatures.

Journal reference: Science, DOI: 10.1126/science.1225354 and 10.1126/science.1225374
 
Dawn probe spies possible water-cut gullies on Vesta
By Jonathan Amos, Science correspondent, BBC News, San Francisco

Scientists say they have seen features on Asteroid Vesta that look as though they could have been cut by some sort of fluid flow - possibly liquid water.
If correct, it is an extraordinary observation because any free water on the surface of the airless body would ordinarily boil rapidly and vaporise.

But pictures of Vesta taken by Nasa's Dawn probe show complex gullies running down the walls of some craters.
The possibility of liquid erosion needs to be considered, say the researchers.
"We want to hear what other people's opinions are," Jennifer Scully, from the University of California, Los Angeles (UCLA), told BBC News.
"We're just putting it out there to the community; we're not suggesting anything hard and fast at this stage."
Ms Scully was speaking here at the American Geophysical Union (AGU) Fall Meeting, the largest annual gathering of Earth and planetary scientists.

The Dawn satellite spent more than a year investigating Vesta, the second largest member in the asteroid belt between Mars and Jupiter.
The probe departed the body this past September, but not before it had mapped most of the surface from an altitude of just 210km.
This allowed the Nasa mission to pick out surface features in fine detail.

Ms Scully examined all of the craters on Vesta that measured about 10km and wider, cataloguing the shapes of the gullies that etched their walls.
In the majority of cases (about 50 examples), the troughs trace simple descent lines and are presumably the consequence of loose rock or soil falling down the slope. But in a second, smaller group (11 examples), the pattern the gullies cut in the surface is quite different. They are complex; they are interlaced.

"The first group we call Type A. They're very typical of dry-mass wasting; the sort of thing you would get on Earth's Moon and on other, smaller asteroids. But the Type B gullies are the ones we think may have this liquid water origin; they have quite distinct morphologies. They are longer and narrower. They also interconnect, branching off one another."

If it was liquid water that carved these features, the question then arises as to its source.
Vesta is recognised generally to be a very dry body. Geological processes in its early history are thought to have driven off the vast majority of its volatile materials.

And in any case, with no pressure from an atmosphere, the asteroid cannot sustain liquid water at its surface for very long. Any such fluid would be lost to space in short order.
This means any reserve of water must be retained beneath the surface.

"[It] would be cool enough just a few metres or even some centimetres beneath the surface that water could be preserved for a long time," said Prof Chris Russell, the principal investigator on the Dawn mission. "So we have some mechanisms like comets that might bring water to the surface - then it could be stored for some period of time."

Perhaps that buried ice later melted and burst out; may be it was water bound up in the rock, in hydrated minerals, that was released by the heating associated with an impact at the surface.

In the near-equatorial Cornelia depression, for example, the Type B gullies tend to form in the dark material that dominates some areas of the crater.
It has been suggested this material is very similar to carbonaceous chondrite meteorites, which can contain a lot of water and the related hydroxyl (OH) mineral.
Could the impact that created Cornelia have temporarily increased local temperatures and pressures sufficiently to allow liquid water briefly to flow and cut the gullies before spontaneously boiling off?

The observations mirror those for Mars back in 2000 when satellite pictures also revealed complex gully systems running down the walls of craters on the Red Planet.
A fierce debate then ensued between those who argued they were water-cut and those who proposed other explanations that did not require water. One alternative proposed that the channels were cut by a tumbling mass of dry material suspended in a flow of carbon dioxide.

The controversy of the Martian gullies prompts Prof Russell to be cautious in the interpretation of the Vesta gullies.
"We want to be very, very sure on any statement or pronouncement we make about the gullies or water or anything like that, because it turns out that there are a lot of different interpretations - we have to work our way through them," he said.

"That's exactly how the scientific method works - we have an idea; we have to test it against the available evidence, and a lot of people are shareholders in that evidence and they will talk to us about what their evidence is," he told BBC News.

http://www.bbc.co.uk/news/science-environment-20582704
 
Astronomers classify asteroids according to their orbit types:

AMOR asteroids have perihelia inside the orbit of Mars: 1.017 < perihelion < 1.3 AU. Over 800 are known.
A few travel out beyond Jupiter's orbit (5.2 AU).
They all have periods greater than one year. (Semimajor axis > 1 AU)

APOLLO asteroids cross the Earth's orbit:
perihelion < 1.017 AU. About 1100 are known.
Some travel out to the orbit of Jupiter (5.2 AU), and one goes beyond Neptune!
They all have periods greater than one year. (Semimajor axis > 1 AU)

ATEN asteroids have semimajor axis < 1 AU: their orbits therefore lie mostly inside that of Earth and they have periods of less than one year. Only about 200 Atens are known - partly because they mostly hide in the daylight sky.

(Apohele asteroids, or alternatively Interior-Earth Objects (IEOs) or Atira asteroids, are a subclass of Aten asteroids. They have not only their perihelion within Earth's orbit, but also their aphelion; that is, their entire orbit is within Earth's (which has a perihelion of 0.983 AU).)

Of these, only the Apollos and Atens are potential Earth-impactors. Apollos are relatively easy to see and predict, but the Atens come at us 'out of the sun' (like a fighter in an aerial dog-fight) and so are very difficult to see or predict. One could wipe us out tomorrow, and then we'd never get to see 2012 DA14 whizz by on Friday! :shock:

We need to find out more about the Atens:
Gaia is a space observatory to be launched by the European Space Agency (ESA) in October 2013. The mission aims to compile a 3D space catalogue of approximately 1 billion stars, or roughly 1% of stars in the Milky Way.
...

Its objectives comprise:

determining the positions, distances, and annual proper motions of 1 billion stars with an accuracy of about 20 µas (microarcsecond) at 15 mag, and 200 µas at 20 mag

detection of tens of thousands of extra-solar planetary systems[4]

capacity to discover Apohele asteroids with orbits that lie between Earth and the Sun, a region that is difficult for Earth-based telescopes to monitor since this region is only in the sky during or near the daytime[5]

detection of up to 500,000 distant quasars

more accurate tests of Albert Einstein’s general relativity theory

...

http://en.wikipedia.org/wiki/Gaia_mission
I'm not sure why Apohele asteroids are mentioned, since they are not dangerous Earth-crossers, unlike the Atens. But if Gaia can find Apoheles, it will also find and track Atens.

At least one Aten, 1999 KW4, is known to be a double body, with diameters of 12 and 0.36 km. Even the smaller body is larger than 2012 DA14, so it would be more than double-trouble if something like that hit Earth! :shock:
 
Freak space rock spins dusty trail

The Hubble telescope has spotted an asteroid radiating six comet-like tails, making it resemble a "rotating lawn sprinkler".
Other asteroids appear as tiny points of light to astronomers, who are puzzled by the outbursts of dust.

Asteroid P/2013 P5 has been ejecting dust periodically for at least five months and may be in the process of breaking up.
They have outlined details in the journal Astrophysical Journal Letters.

"We were literally dumbfounded when we saw it," said Prof Dave Jewitt, from the University of California at Los Angeles.
"Even more amazing, its tail structures change dramatically in just 13 days as it belches out dust. That also caught us by surprise. It's hard to believe we're looking at an asteroid."

Astronomers say it is possible the asteroid's rotation rate increased to the point where its surface started flying apart.
Radiation pressure from the Sun could have sent the space rock spinning, to a point where the asteroid's weak gravity could no longer hold it together.

Astronomers will continue observing P/2013 P5 to see whether the dust leaves the asteroid in the equatorial plane. Because of the physics involved in the spin rate theory, say the astronomers, this would provide strong evidence for a rotational breakup.

They do not believe the tails are the result of an impact with another asteroid because they have not seen a large quantity of dust blasted into space all at once.

Astronomers discovered the object in August, using the Pan-STARRS telescope in Hawaii. At the time, P/2013 P5 looked unusually fuzzy.
The multiple tails were discovered when Hubble was used to take a more detailed image on 10 September.

http://www.bbc.co.uk/news/science-environment-24857869
 
I thought this was the big discovery....
:?

First Ring System Around Asteroid
Chariklo found to have two rings

26 March 2014
Click to Enlarge

Observations at many sites in South America, including ESO’s La Silla Observatory, have made the surprise discovery that the remote asteroid Chariklo is surrounded by two dense and narrow rings. This is the smallest object by far found to have rings and only the fifth body in the Solar System — after the much larger planets Jupiter, Saturn, Uranus and Neptune — to have this feature. The origin of these rings remains a mystery, but they may be the result of a collision that created a disc of debris. The new results are published online in the journal Nature on 26 March 2014.

The rings of Saturn are one of the most spectacular sights in the sky, and less prominent rings have also been found around the other giant planets. Despite many careful searches, no rings had been found around smaller objects orbiting the Sun in the Solar System. Now observations of the distant minor planet [1] (10199) Chariklo [2] as it passed in front of a star have shown that this object too is surrounded by two fine rings.

"We weren’t looking for a ring and didn’t think small bodies like Chariklo had them at all, so the discovery — and the amazing amount of detail we saw in the system — came as a complete surprise!" says Felipe Braga-Ribas (Observatório Nacional/MCTI, Rio de Janeiro, Brazil) who planned the observation campaign and is lead author on the new paper.

Chariklo is the largest member of a class known as the Centaurs [3] and it orbits between Saturn and Uranus in the outer Solar System. Predictions had shown that it would pass in front of the star UCAC4 248-108672 on 3 June 2013, as seen from South America [4]. Astronomers using telescopes at seven different locations, including the 1.54-metre Danish and TRAPPIST telescopes at ESO’s La Silla Observatory in Chile [5], were able to watch the star apparently vanish for a few seconds as its light was blocked by Chariklo — an occultation [6].

But they found much more than they were expecting. A few seconds before, and again a few seconds after the main occultation there were two further very short dips in the star’s apparent brightness [7]. Something around Chariklo was blocking the light! By comparing what was seen from different sites the team could reconstruct not only the shape and size of the object itself but also the shape, width, orientation and other properties of the newly discovered rings.

The team found that the ring system consists of two sharply confined rings only seven and three kilometres wide, separated by a clear gap of nine kilometres — around a small 250-kilometre diameter object orbiting beyond Saturn.

"For me, it was quite amazing to realise that we were able not only to detect a ring system, but also pinpoint that it consists of two clearly distinct rings," adds Uffe Gråe Jørgensen (Niels Bohr Institute, University of Copenhagen, Denmark), one of the team. "I try to imagine how it would be to stand on the surface of this icy object — small enough that a fast sports car could reach escape velocity and drive off into space — and stare up at a 20-kilometre wide ring system 1000 times closer than the Moon." [8]

Although many questions remain unanswered, astronomers think that this sort of ring is likely to be formed from debris left over after a collision. It must be confined into the two narrow rings by the presence of small putative satellites.

"So, as well as the rings, it’s likely that Chariklo has at least one small moon still waiting to be discovered," adds Felipe Braga Ribas.

The rings may prove to be a phenomenon that might in turn later lead to the formation of a small moon. Such a sequence of events, on a much larger scale, may explain the birth of our own Moon in the early days of the Solar System, as well as the origin of many other satellites around planets and asteroids.

The leaders of this project are provisionally calling the rings by the nicknames Oiapoque and Chuí, two rivers near the northern and southern extremes of Brazil [9].
Notes

[1] All objects that orbit the Sun, which are too small (not massive enough) for their own gravity to pull them into a nearly spherical shape are now defined by the IAU as being small solar system bodies. This class currently includes most of the Solar System asteroids, near-Earth objects (NEOs), Mars and Jupiter Trojan asteroids, most Centaurs, most Trans-Neptunian objects (TNOs), and comets. In informal usage the words asteroid and minor planet are often used to mean the same thing.

[2] The IAU Minor Planet Center is the nerve centre for the detection of small bodies in the Solar System. The names assigned are in two parts, a number — originally the order of discovery but now the order in which orbits are well-determined — and a name.

[3] Centaurs are small bodies with unstable orbits in the outer Solar System that cross the orbits of the giant planets. Because their orbits are frequently perturbed they are expected to only remain in such orbits for millions of years. Centaurs are distinct from the much more numerous main belt asteroids between the orbits of Mars and Jupiter and may have come from the Kuiper Belt region. They got their name because — like the mythical centaurs — they share some characteristics of two different things, in this case comets and asteroids. Chariklo itself seems to be more like an asteroid and has not been found to display cometary activity.

[4] The event was predicted following a systematic search conducted with the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory and recently published.

[5] Besides the Danish 1.54-metre and TRAPPIST telescopes at ESO's La Silla Observatory, event observations were also performed by the following observatories: Universidad Católica Observatory (UCO) Santa Martina operated by the Pontifícia Universidad Católica de Chile (PUC); PROMPT telescopes, owned and operated by the University of North Carolina at Chapel Hill; Pico dos Dias Observatory from the National Laboratory of Astrophysics (OPD/LNA) - Brazil; Southern Astrophysical Research (SOAR) telescope; Caisey Harlingten's 20-inch Planewave telescope, which is part of the Searchlight Observatory Network; R. Sandness's telescope at San Pedro de Atacama Celestial Explorations; Universidade Estadual de Ponta Grossa Observatory; Observatorio Astronomico Los Molinos (OALM) — Uruguay; Observatorio Astronomico, Estacion Astrofisica de Bosque Alegre, Universidad Nacional de Cordoba, Argentina; Polo Astronômico Casimiro Montenegro Filho Observatory and Observatorio El Catalejo, Santa Rosa, La Pampa, Argentina.

[6] This is the only way to pin down the precise size and shape of such a remote body — Chariklo is only about 250 kilometres in diameter and is more than a billion kilometres from Earth. Even in the best telescopic views such a small and distant object just appears as a faint point of light.

[7] The rings of Uranus, and the ring arcs around Neptune, were found in a similar way during occultations in 1977 and 1984, respectively. ESO telescopes were also involved with the Neptune ring discovery.

[8] Strictly speaking the car would have to be rather fast — something like a Bugatti Veyron 16.4 or McLaren F1 — as the escape velocity is around 350 km/hour!

[9] These names are only for informal use, the official names will be allocated later by the IAU, following pre-established rules.
More information

This research was presented in a paper entitled “A ring system detected around the Centaur (10199) Chariklo”, by F. Braga-Ribas et al., to appear online in the journal Nature on 26 March 2014.


http://www.eso.org/public/news/eso1410/
 
Another icy rock in the outer Solar System? Seems a bit of a build up for something relatively mundane. I prefer Vardoger's asteroid rings.
 
Looks like the Brazilians were trumped by other astronomers with the icy mini planet news.
 
Protoplanet Vesta, visited by NASA's Dawn spacecraft from 2011 to 2013, was once thought to be completely dry, incapable of retaining water because of the low temperatures and pressures at its surface. However, a new study shows evidence that Vesta may have had short-lived flows of water-mobilized material on its surface, based on data from Dawn.

"Nobody expected to find evidence of water on Vesta. The surface is very cold and there is no atmosphere, so any water on the surface evaporates," said Jennifer Scully, postgraduate researcher at the University of California, Los Angeles. "However, Vesta is proving to be a very interesting and complex planetary body."

The study has broad implications for planetary science. ...

http://phys.org/news/2015-01-gullies-vesta-water-mobilized.html
 
Asteroid that could 'injure THOUSANDS' to skim Earth TONIGHT two days after its discovery
AN ASTEROID that no one knew existed until two days ago and is on an unpredictable course is set to skim past Earth within hours.
By Jon Austin
PUBLISHED: 00:12, Sat, Dec 19, 2015 | UPDATED: 01:32, Sat, Dec 19, 2015

Slooh-Asteroid-628045.jpg
GETTY

The asteroid was discovered just two days ago
Astronomers were oblivious to the existence of the space rock, which is big enough to destroy a town and called 2015 YB, until Wednesday.

The Slooh Telescope internet channel is hosting a special live broadcast to capture the flyby at 2am.

A Slooh spokesman said the pass was so near it would be within range of geosynchronous satellites which orbit at the same rotation period as Earth.

He said: "Discovered just two days ago, Slooh will provide live coverage.

"The size and speed of this asteroid makes it very difficult to track.

"During our live broadcast, host Paul Cox and Slooh Astronomer Bob Berman will discuss why it is so difficult to track these fast moving objects, and of course, the kind of damage a (it) would cause were it to impact Earth, and why."

It may sound far, but the estimated 34,672 miles away pass, its a cat's whisker in cosmic terms, and is less than a fifth of the 238,000 miles between earth and the moon.

The asteroid is only 20 metres in length, but an asteroid of the same size exploded suddenly in Earth's atmosphere above Chelyabinsk, Russia, in February 2013 - injuring 1,500 people.

If an asteroid of 50 metres hit London it could destroy the city.

Astronomers have nicknamed the asteroid The Flea, in honour of the world's greatest soccer player, Lionel Messi.

The spokesman added: "We will be asking, why, like Messi, it got through our best defences until two days ago."

To watch the broadcast click back on this story at 2am, Saturday, December 19.

Viewers can ask questions and interact with the hosts on Twitter via @Slooh.

It is the second recent near Earth asteroid to turn up out of the blue.

http://www.express.co.uk/news/science/628045/Asteroid-could-injure-THOUSANDS-skim-Earth-TONIGHT-two-days-after-its-discovery
 
Slooh's own page on this:
ASTEROID ALERT!!

Discovered just 2 days ago, Slooh will provide live coverage tonight at 9pm EST of tiny asteroid 2015 YB (26-59 feet long), nicknamed “The Flea”, which will pass just 34,672 miles (0.2 lunar distances) from Earth, bringing it almost in range of our geosynchronous satellites which orbit at 22,000 miles. Named in honor of the world’s greatest soccer player Lionel Messi, the size and speed of this asteroid makes it very difficult to track.
During our live broadcast, tonight at 9 PM EST / 6 PM PST / 02:00UTC (12/19), host Paul Cox and Slooh Astronomer Bob Berman will discuss why it is so difficult to track these fast moving objects, and of course, the kind of damage a Flea like this would cause were it to impact Earth, and why like Messi it got through our best defenses sight unseen until 2 days ago.

Slooh has been tracking asteroids for years, and has gained quite the reputation for capturing this fast moving space rocks live. Most recently, we watched ‘Spooky’ the Halloween Asteroid fly by the Earth. We’ve also tracked ‘Pitbull‘, The $5 Trillion Asteroid, ‘The Beast‘ and many others. You can also read about the Space Act Agreement we signed with NASA to help protect Earth from near-Earth asteroids.

http://main.slooh.com/event/tracking-2015-yb-the-flea-on-close-approach/
 
Mysterious 'exiled' asteroid found in far reaches of solar system

The first of its kind to be found so far away, 2004 EW95 is a carbon-rich asteroid that currently resides in the Kuiper Belt, a cold region beyond the orbit of Neptune.


Astronomers suspect the 300km-long object was formed in the asteroid belt between Mars and Jupiter before being ejected into the outer reaches of the solar system.


While performing routine observations using the Hubble Space Telescope, Queen's University Belfast astronomer Dr Wesley Fraser noticed something unusual about one of the distant asteroids he was monitoring.


Its “reflectance spectrum” – the pattern of light reflecting from it – marked it out from neighbouring bodies.


"It looked enough of a weirdo for us to take a closer look."


Measurements taken using the European Southern Observatory’s (ESO) Very Large Telescope allowed the team to determine it was formed from carbon, suggesting it originated in the inner solar system.


This idea was confirmed by the presence of minerals called ferric oxides and phyllosilicates, which had never been confirmed before in an asteroid from the Kuiper Belt and are another indicator it first emerged closer to the Sun.


Astronomers suspect the 300km-long object was formed in the asteroid belt between Mars and Jupiter before being ejected into the outer reaches of the solar system.


As gas giants such as Jupiter and Saturn formed, they are thought to have migrated through the solar system, causing chaos as they flung small rocky bodies like 2004 EW95 from their places of origin into the solar system’s outer regions.


"The reflectance spectrum of 2004 EW95 was clearly distinct from the other observed outer solar system objects," said Dr Tom Seccull, another Queen's University Belfast and lead author of the study describing the new asteroid.

"Given 2004 EW95's present-day abode in the icy outer reaches of the solar system, this implies that it has been flung out into its present orbit by a migratory planet in the early days of the solar system,” said Dr Seccull.

If this is the case, then astronomers should expect to find more 2004 EW95-like bodies in the Kuiper Belt, but so far it is the only known example.

The lack of fellow asteroids from the inner solar system does not mean 2004 EW95 is alone – it simply exemplifies the difficulty in observing objects that are so far away, even with the very best technology available.


"It's like observing a giant mountain of coal against the pitch-black canvas of the night sky," said Professor Thomas Puzia from the Pontificia Universidad Católica de Chile, who co-authored the study.
 
To The Asteroid Belt!

The asteroid belt is rich with precious metals. There are already plans for asteroid mining but could we ever build a colony on one?

The science-fiction series The Expanse is set 200 years in the future: humans have established colonies on the Moon and Mars, and have begun colonising the asteroid belt.

There are compelling reasons why we might wish to colonise the asteroid belt, but the predominant one is mining. Unlike the Earth, where precious metals tend to be buried underground, there is an abundance of metals like gold and palladium on the surface of asteroids. But they could also be used as a scientific research outpost.

The Asteroid Belt orbits the Sun between Mars and Jupiter, and is thought to be the remains of a planet. While the Asteroid Belt is the main source of asteroids, asteroids can be found throughout the Solar System and come in three basic types; stony, carbonaceous and metallic. They range in size from hundreds of metres to the size of a small house. ...

http://www.bbc.com/future/story/20180612-will-we-ever-colonise-an-asteroid
 
NASA's OSIRIS-REx spacecraft arrives at asteroid Bennu

Hopefully it'll turn out to be a starship.

Some interesting news about Bennu.

THE WOODLANDS, TEXAS—NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) mission to sample the asteroid Bennu and return to Earth was always going to be a touch-and-go maneuver. But new revelations about its target—a space rock five times the size of a U.S. football field that orbits close to Earth—are making the mission riskier than ever. Rather than smooth plains of rubble, Bennu’s surface is a jumble of more than 200 large boulders, with scarcely enough gaps for robotic sampling of its surface grit, the spacecraft’s team reported here today at the Lunar and Planetary Science Conference and in a series of Nature papers.

The $800 million spacecraft began to orbit Bennu at the start of this year, and the asteroid immediately began to spew surprises—literally. On 6 January, the team detected a plume of small particles shooting off the rock; 10 similar events followed over the next month. Rather than a frozen remnant of past cosmic collisions, Bennu is one of a dozen known “active” asteroids. “[This is] one of the biggest surprises of my scientific career,” says Dante Lauretta, the mission’s principal investigator and a planetary scientist at the University of Arizona in Tucson. “We are seeing Bennu regularly ejecting material into outer space.” ...

https://www.sciencemag.org/news/201...activity-complicates-nasa-s-sampling-attempts
 
Hopefully the asteroid isn't a concealed Alien Starship/Base. They might regard it as a Pearl Harbour style incident.

The Japanese Hayabusa-2 spacecraft is thought to have detonated an explosive charge on the asteroid it is exploring.

Its mission is to create an artificial crater on the asteroid Ryugu. If this is successful, it will later return to gather samples of the asteroid, which could help scientists understand how Earth was formed in the early Solar System.

According to Kyodo News, the experiment's success will only be confirmed in late April.

The explosive device, called the Small Carry-on Impactor (SCI), was deployed by the Hayabusa-2 on Friday. The SCI is a 14kg conical container attached to the Hayabusa-2 and packed with plastic explosive. It was intended to punch a 10m-wide hole in the asteroid upon impact.

The SCI on Friday successfully separated from the Hayabusa-2 at an altitude of 500m above the surface of Ryugu.

https://www.bbc.com/news/science-environment-47818460
 
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Some interesting news about Bennu.

THE WOODLANDS, TEXAS—NASA’s Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) mission to sample the asteroid Bennu and return to Earth was always going to be a touch-and-go maneuver. But new revelations about its target—a space rock five times the size of a U.S. football field that orbits close to Earth—are making the mission riskier than ever. Rather than smooth plains of rubble, Bennu’s surface is a jumble of more than 200 large boulders, with scarcely enough gaps for robotic sampling of its surface grit, the spacecraft’s team reported here today at the Lunar and Planetary Science Conference and in a series of Nature papers.

The $800 million spacecraft began to orbit Bennu at the start of this year, and the asteroid immediately began to spew surprises—literally. On 6 January, the team detected a plume of small particles shooting off the rock; 10 similar events followed over the next month. Rather than a frozen remnant of past cosmic collisions, Bennu is one of a dozen known “active” asteroids. “[This is] one of the biggest surprises of my scientific career,” says Dante Lauretta, the mission’s principal investigator and a planetary scientist at the University of Arizona in Tucson. “We are seeing Bennu regularly ejecting material into outer space.” ...

https://www.sciencemag.org/news/201...activity-complicates-nasa-s-sampling-attempts


Bennu is literally exploding with news.

For the last year, NASA’s OSIRIS-REx spacecraft has been circling a large asteroid named Bennu that regularly passes uncomfortably
close to Earth. The spacecraft has been painstakingly mapping the asteroid’s rocky surface using a suite of cameras and other instruments that will help it determine where to land next year. Once NASA selects a final landing site, OSIRIS-REx will kiss Bennu just long enough to scoop up a sample to bring back to Earth in 2023.

Many scientists expect the Bennu sample to revolutionize our understanding of asteroids, especially those that are near Earth and pose the greatest threat to life as we know it. But as detailed in a paper published today in Science, NASA has already started making surprising discoveries around this alien world. Earlier this year, the OSIRIS-REx team witnessed particles exploding from the asteroid’s surface—and it’s not sure why.

“No one has ever seen an active asteroid up close like this,” says Carl Hergenrother, an astronomer at the University of Arizona and the scientist who proposed Bennu as the target for OSIRIS-REx. “It wasn’t that long ago that the conventional wisdom was that asteroids are these dead bodies that didn’t change very much.”

In January, the navigation cameras on OSIRIS-REx captured three ejection events that each spewed about 100 centimeter-sized asteroid particles into space. The spacecraft also detected a significant number of particles already orbiting Bennu like a cloud of gnats. Their diverse orbits suggest that particle ejections are a common event on the asteroid and occur all across its surface, rather than in a few select spots. Indeed, in the year since the three ejection events that are reported today in Science, Hergenrother says OSIRIS-REx has detected several other smaller ejections. ...

https://www.wired.com/story/no-one-knows-why-rocks-are-exploding-from-asteroid-bennu/
 
Asteroid in unusual orbit.

For the first time, an asteroid has been found orbiting closer to the sun than Venus — a neighborhood where asteroids are thought to be rare and tricky to find.

The space rock, designated 2020 AV2, orbits the sun once every 151 days along an elongated trajectory that keeps it between the orbits of Mercury and Venus. Such asteroids — known as Vatiras — were first predicted in 2012, but until now, no one had ever found one.

Asteroid 2020 AV2 was found January 4 by researchers at the Palomar Observatory in southern California. Following an alert by the International Astronomical Union’s Minor Planet Center, observers around the world confirmed and refined the asteroid’s orbit.

Asteroids that live inside Earth’s orbit are notoriously difficult to find because they spend most of their time close to the sun (SN: 4/3/15). Astronomers can therefore look for such objects only during brief periods of twilight.

According to computer simulations, Vatiras are rare, making up only 0.22 percent of so-called near-Earth objects. Vatiras probably start their lives in the main asteroid belt between Mars and Jupiter and end up between Mercury and Venus after a series of close encounters with rocky planets.

https://www.sciencenews.org/article/first-time-asteroid-has-been-found-nearer-sun-than-venus
 
The recent visit by 'Oumuamua raised the question of how many other interstellar visitors were hanging out in our solar system, having been captured by our star's gravity. Astronomers have now assembled a list of 19 asteroids they suspect are "foreign."
Astronomers Just Identified 19 More Asteroids They Think Are Interstellar

The Solar System has been here for a long time. So, when 'Oumuamua was spotted in 2017, it was almost a dead cert it wasn't the only object from interstellar space to visit us over that 4.57 billion-year history. Then comet 2I/Borisov showed up last year. That basically clinched it.

But where are the rest of our interstellar visitors? We'll probably find a few more flying in from the wilds in the coming years. And, according to new research, a whole bunch of interstellar asteroids have been hanging out right here in the Solar System for a very long time.

Based on how they move around the Sun, a team of researchers has identified 19 asteroids they think were captured from another star, way back when the Solar System was just a few million years old. ...
FULL STORY: https://www.sciencealert.com/astron...19-more-asteroids-they-think-are-interstellar
 
The asteroid ES04 2011 is approaching. Around September 1st it should pass about 40,000 miles from Earth, possibly within the Moon's orbit.
It is as big as a cathedral and we are all doomed. Doomed, I tell'ee.
 
The asteroid ES04 2011 is approaching. Around September 1st it should pass about 40,000 miles from Earth, possibly within the Moon's orbit.
It is as big as a cathedral and we are all doomed. Doomed, I tell'ee.

Cromer deserves o have a cathedral.
 
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