Astronomical News

rynner2

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#1
(It's happening right now.)
Showtime for Mercury

The planet Mercury is passing in front of the Sun as viewed from Earth.

The event, called a transit, occurs only about 12 times a century.

Mercury began the journey across the star's disc at just after 0510 GMT, depending on the viewing location on Earth - although astronomers stress no one should look towards the Sun with the unaided eye.

Some part of the five-hour trek is visible from the whole world except Antarctica and the western parts of the Americas. Europe, Asia and Africa are most favoured.

Skygazers without access to proper equipment are strongly recommended to watch the event only on the internet.

Venus show

The websites of several organisations, including the European Southern Observatory (Eso) and the Solar and Heliospheric Observatory (Soho), are streaming the transit live.

"People will see a small, perfectly round, black dot slowly moving across the solar disc," said US space agency eclipse expert Fred Espenak.

The planets Mercury and Venus are the only ones that appear to cross the face of the Sun, as seen from Earth, since both are closer to the star than Earth.

In the case of Mercury, transits occur either close to 7 May at intervals of 13 and 46 years or close to 9 November, which occur more frequently at intervals of 7, 13 and 46 years.

Venus transits are also rare, with just one pair eight years apart every 105 to 121 years.

"The last Venus transit was in 1882, so no one alive has seen one," said Espenak.

Scientific importance

PLANET MERCURY

57.9m km from Sun
Mercury year lasts 88 Earth days
Surface temperature is about 170C compared with Earth's 15C
"Happily, there will be a Venus transit on 8 June, 2004, so this year's Mercury transit can be taken as an appetizer for the main course."

Edmund Halley first realised that transits could be used to measure the Sun's distance, thereby establishing the absolute scale of the Solar System.

The 1761 and 1769 expeditions to observe the transits of Venus gave astronomers their first good value for the Sun's distance.

Spacecraft have visited Mercury only once - the US Mariner 10 mission in 1974-75.

Two future missions to Mercury are being planned.

The US Mercury Messenger probe is due for a 2004 launch and 2009 arrival. The European BepiColombo mission will be launched 2011-12 and arrive 2015-16.

UK astronomers, students and members of the public will be watching the transit of Mercury in an open event at the Royal Observatory Greenwich in London.
BBC link I'll look for a web link to follow this event on.

And just for Fortean interest, what significance do astrologers put on such a precise conjunction?


EDIT: Several links available, but internet traffic seems heavy! try this Dutch one
 

rynner2

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#2
Here's a screenshot of one of the recent SOHO images -

exciting, isn't it! :D

(It seems that the various images are presented in different orientations - but there are no sunspots near Mercury, so its movement will be seen as time passes.)
 
A

Anonymous

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#3
Fiddlesticks! I've missed it.

Very interesting, but I am puzzled as to why the event occurs so rarely. I have a reasonable knowledge of astronomy, and I've always thought that since the planets are all orbiting roughly in the same plane* (close to the plane of the ecliptic) Mercury and Venus ought to pop in front of the sun, from our viewpoint, very frequently. Mercury ought to do it 3 or 4 times a year, and Venus at least once a year. I guess the orbits must be tilted a bit more than I thought, unless there's something very obvious I'm missing.

Hi from Bulgaria. :)

Bill Robinson

* Except for Pluto of course.
 

mejane

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#4
rynner said:
Here's a screenshot of one of the recent SOHO images -

exciting, isn't it! :D
Yep :) It would have been even better if there weren't so many clouds this morning (or maybe I should have got up a bit earlier...)

I've no idea what astrologers make of it, but why doesn't anyone ever say "the two inner planets are not the same apparent size as the sun, unlike the moon - isn't that weird!".

Bill, :hello: from England - hope you had better weather this morning. Venus, Mercury, the moon and that strange blue-green planet called Earth are all in elipital (sp?) orbits, not perfectly round ones. Hence the infrequency of eclipses.

Jane.
 

taras

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#5
What's so exciting about it? I'm interested in astronomy but to me it just seems like the same unfounded excitement as reaching a round number... :eek:
 

mejane

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#6
taras said:
What's so exciting about it? I'm interested in astronomy but to me it just seems like the same unfounded excitement as reaching a round number... :eek:
It's just nice to see the universe doing it's best to confound and confuse us :)

Historically, the transits of Venus & Mercury not only proved the existence of other planets (and hence that the Earth is not the centre of all things) but the measurements of their progress (and their rarity) showed that the Universe is not a perfect mechanical model - Pi is not 3, it's far more interesting than that.

Or maybe I'm just a geek :D

Jane.
 

rynner2

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#7
Orbital inclinations to the ecliptic (the plane of Earth's orbit):

Venus - 3 deg 24 min
Mercury - 7 deg

So most times they are in conjunction with the sun, they are well north or south of it. A transit only occurs when the conjunction occurs at the same time the planet is also very near the ecliptic (which only happens twice an orbit).

Transits of Venus occur in pairs 8 years apart, with over a century to the next pair. (These will be in 2004 and 2012.)

Mercury transits at intervals of 7 and 13 years.
 
A

Anonymous

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#8
Mercury- a very valuable world.
Hot and dry, ok, but well placed to intercept solar energy, and full of the heavier elements that were not expelled from the inner system when the Sun ignited.

Ultimately the best thing to do with this world would be to utilise the solar energy to disassemble Mercury and build a Dyson Swarm...
this could be achieved in a few centuries using mass drivers.
as you can see from the SOHO image, this tiny speck would barely make a shadow on that great fireball, even if broken up into slabs.
 

Philo_T

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#9
Also don't forget Fort's writings on astronomy. He really liked getting digs in at the astronomers. Possibly because that was the height of Victorian rationalism -- and not without dogism.

1. Reports of the planet Vulcan and other inter-Mecurical bodies noted during observations of transits.
2. The timing of the transit of Mecury provided important data to Einstien in the development of the theory of relativity
3. All sort of weird reports of bodies, even trains of bodies anomylously crossing the Sun get noticed while everyone's looking that way. (I often wonder if anything similar turns up on SOHO, or if many such reports are actually of objects within our atmosphere.)
4. Fort's Monstro (sp)
 

littleblackduck

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#11
Astrology, Astronomy, let's call the whole thing off!

Mercury - the metal, Mercury - the God, Mercury - the Planet, and Mercury - the Astrological Planet, not to mention the Sun--the sky is mighty crowded when planets transit.

Which is definitely one of Charles Fort's private theories. Vulcan and all his lesser minions are just the start for Fort--there's sunspots that move too quickly, other spots that move too slowly, observations of Mercury and Venus transiting at the wrong time, speed or place--it gets confusing.

Mercury governs children, travellers, thieves, merchants, literature, scribes, etc.

The Sun governs the arts, music, affairs of state, secular and religious powers-that-be, gold and what not.

Astrologers will look for, and find, sudden and dramatic changes in the affairs of all of these (hard not to, seeing as the two planets seem to have a hand in everything).

Astronomers will look for and find confirmation of their theories.

Fort will have a good laugh.

My predictions:
The Money stolen from the Iraqi Central Bank ($900 million U.S.) will turn up in the purse of Martha Stewart.

Geo. W. Bush will leave his wife Laura for J.K. Rowling, causing the intellectual equivalent of a Black Hole, which will suck everything into it.

Children will be subject to sudden and unexpected movements, startling old people.

But seriously, the time lapse picture of the early stages of the transit which I saw yesterday had several other bodies leaving a trail of dots on the Sun, besides Mercury, and they were much more interesting dots at that. Too bad Fort isn't alive to propose a theory as to what exactly they are and why the scientists and journalists neglected to offer explanations.
 

drjbrennan

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#13
It is a little known fact that the reason for Captain Cooks voyage, during which he also discovered Australia, was to make observations of the transit of venus in the southern hemisphere.
 

rynner2

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#14
"I knew tha-a-at!"

(Also the reason the Shuttle 'Endeavour' is spelt the British way, and not 'Endeavor' - it was named after Cook's ship.)
 

DerekH16

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#16
And I thought I'd killed this thread :rolleyes:

And wasn't the 'Interflora' guy Apollo, rather than Mercury?

I'm trying, ... really, really trying !!
 

rynner2

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#18
SPECIAL INTEREST: The Sky at Night
Channel: BBC 2
Date: Saturday 10th May 2003
Time: 12:45 to 13:05 (starting in 4 hours and 9 minutes)
Duration: 20 minutes.
(The Early Bird)
Patrick Moore takes a look at three astronomical events which can all be witnessed from Britain: the transit of Mercury, a lunar eclipse and an annular eclipse.
(Repeat, Subtitles)

Excerpt taken from DigiGuide
 

Mal_Adjusted

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#19
Greets

decided to have a thread where updates in the "world" of astronomy can be posted (as opposed to seperate threads where few people comment)

Astronomers Identify Trio of Supergiant Stars
Mon Jan 10, 2005 12:24 PM ET


An international team of astronomers, including Massey, looked at a field of 74 supergiant stars to try to learn more about them. The scientists knew the stars' distance from Earth, and they knew how bright they were, but they didn't know just how cool they were.

In the case of stellar temperatures, cool is a relative term. These stars are around 5,600 degrees Fahrenheit. The sun is nearly 10,000 degrees F and the hottest known stars are more than 90,000 degrees F.

Knowing the temperature was important, Massey said, because a fundamental law of stellar physics holds that a star's brightness is proportional to its temperature and size. By knowing two of these numbers, scientists could find out the third with precision.

The team used new computer models that have improved data on molecules in the outer layers of these big stars, and found that in fact the trio were about 10 percent warmer than researchers had expected. They were also able to calculate their size, Massey said in a telephone interview from Flagstaff, Arizona, where he works at Lowell Observatory.

"I think the interesting aspect of this is that it tells us the extreme that normal stars can become, how large a normal star of any kind can ever become," Massey said.

All the stars in the study were normal stars, that is, none were two-star pairs known as binaries, whose parameters could be different.


Will this ever happen to our sun? In a word, no.

The sun simply lacks the mass to become a red supergiant, Massey said.

The three big supergiant stars are: KW Sagitarii, which is 9,800 light-years from Earth; V354 Cephei, at 9,000 light-years away; and KY Cygni, 5,200 light-years away.

A light-year is about 6 trillion miles, the distance light travels in a year.



http://www.reuters.com/newsArticle.jhtml?type=scienceNews&storyID=7282839

mal
 

Mal_Adjusted

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#21
Scientists Spy Cosmic Waves Around Black Hole

Greets

Scientists Spy Cosmic Waves Around Black Hole
Mon Jan 10, 2005 06:52 PM ET

MORE


By Deborah Zabarenko

SAN DIEGO (Reuters) - Black holes may actually drag the fabric of space and time around them as they spin, creating waves for cosmic material to surf on, astronomers said on Monday.

This is new evidence that some black holes spin, even as they pull in everything around them, including light. Additional research shows that black holes can twirl material at tremendous speed, as fast as 20,000 miles per second.

"Gas whipping around the black hole has no choice but to ride that wave," Jon Miller of the Harvard-Smithsonian Center for Astrophysics said. "Albert Einstein predicted this over 80 years ago, and now we are starting to see evidence for it."

Because black holes draw in everything, even light, they themselves are invisible. But astronomers have long studied what happens just outside the black hole, and have found what they call an accretion disk -- a round pancake of material, often made up of material sucked from a nearby star that acts as a black hole's companion and food source.

One characteristic that astronomers watch at the mouth of black holes is the flickering of X-ray light. It would make sense that the flickers would come very fast, since black holes spin so rapidly.

It was more puzzling when the flickering X-rays came more slowly, at as little as one 100th the speed of the fast flickers, Miller told reporters at a meeting of the American Astronomical Society.

Miller and his colleagues theorize that in one black hole system they studied, the slower flickering could be the frequency of a space-time warp. In that case, the flickers -- known as quasi-periodic oscillations -- could be caused by the fabric of space itself churning around the black hole in a wave.

Another team of researchers studying a different black hole detected three sun-sized blobs of gas whirling around in the hole's accretion disk.

By looking at iron atoms, which are good markers for what is occurring around a black hole, the scientists figured that these blobs made one complete trip around the black hole in a day, at speeds up to 20,000 miles per second.

Since these blobs were about as far from the black hole as Jupiter is from the sun, this was remarkable, said Jane Turner of NASA's Goddard Space Flight Center. It takes Jupiter 12 years to go around the sun.

The whole system that includes the black hole is relatively tiny, about the size of our solar system, Turner said.

More information and images of a black hole's cosmic wave are available online at http://www.cfa.harvard.edu/press/pr0501image.html.
http://www.reuters.com/newsArticle.jhtml?type=scienceNews&storyID=7285727

mal
 

Timble2

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#23
At last they might have actually seen an extrasolar planet rather than decuded them from their effects.

First direct sighting of an extrasolar planet
11:42 11 January 2005
NewScientist.com news service
Maggie McKee

The Hubble infrared image of brown dwarf 1207 (dimmed in centre) shows its giant planet companion as a magenta spot (Image: NASA/ESA/G Schneider, University of Arizona)Astronomers have directly observed an extrasolar planet for the first time, but are at a loss to explain what they see.

More than 130 planets have been detected orbiting stars other than our own, the Sun. But because the stars far outshine the planets, all of the planets were detected indirectly - by how much they made their host stars wobble or dim, for example.

Now, astronomers say they are almost certain they have snapped an actual image of an extrasolar planet. It was first seen at infrared wavelengths with the Very Large Telescope in Chile in April 2004, and announced at the American Astronomical Society annual meeting in San Diego, California, US on Monday. It appeared alongside a brown dwarf - an astronomical object with a mass inbetween that of a planet and a star.

But astronomers could not immediately confirm that the planet was gravitationally linked to the brown dwarf. So in August 2004, researchers used the Hubble Space Telescope's Near Infrared Camera and Multi-Object Spectrometer to observe the pair again. And they found them in the same relative positions, as would be expected for objects in an estimated 2500-year orbit.

If the finding is borne out by further Hubble observations in April 2005, the images could also reveal information about any atmosphere the planet might have, says team member Glenn Schneider of the University of Arizona, US. Dust clouds, for example, could absorb certain wavelengths of light and leave behind a particular spectral signature, he says.

Several factors helped make the find possible. The fact that the planet - which is five times as massive as Jupiter - orbits a brown dwarf made it stand out more easily. Brown dwarfs, unlike stars, do not burn hydrogen and are therefore relatively dim.

It also lies about 7.5 billion kilometres away from the brown dwarf, which is called 2MASSWJ 1207334-393254 ("1207" for short). That distance - about a third farther than Pluto is from our Sun - helped astronomers visually distinguish the two objects.

But the great distance also puzzles the team, as planets in most solar systems, including our own, tend to lie much nearer their host stars. "They may have formed closer in and [the planet] migrated outward," says team member Eric Becklin, an astronomer at the University of California in Los Angeles, US.

Indeed, simulations suggest pairs of planets about the size of Jupiter can interact as solar systems take shape, with the more massive one being flung outward and the smaller one being hurled toward the star. But it remains possible that "planets may be forming out there" at surprisingly large distances, says Schneider.

Astronomers do not know whether brown dwarfs form in a similar way to stars - though much less spectacularly - or like planets out of a dusty disc. But Hubble observations hint that this brown dwarf may have formed like a star, in a group of young stars about 8 million years old.

The team has been observing 116 nearby stars and brown dwarfs with Hubble since July 2004. So far, they have seen three other candidate planets, all around conventional stars. Follow-up observations with Hubble will confirm whether these are real planets or background objects.
New Scientist
 

rynner2

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#24
Beautiful clear night here - I have a good view of the Orion-Hyades bit of the sky. Is that comet still about? (I know it's getting further off now.)

PS: Just found this:
http://www.astronomynow.com/alerts.shtml#comet

PPS: Drat! That area of sky is almost overhead - not good for scanning with bins, not with my bad neck! :(
 
A

Anonymous

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I saw the comet two nights ago; still perfectly visible in binoculars; I expect those of you in dark sky areas can still see it with the naked eye. Almost straight overhead at eight thirty- about five degrees northwest of the Pleiades.
 

rynner2

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#26
I'll try again tonight (if clear) as soon as it gets dark, when the ghostly crittur should be lower in the sky!
 

tzb57r

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#27
Rynner Said:
PPS: Drat! That area of sky is almost overhead - not good for scanning with bins, not with my bad neck!
Try a sun lounger.... No I'm serious. You can't do it for long when it's really cold and your neighbours will look at you funny, but it does work for looking at objects higher in the sky and also saves peering through so much atmosphere/haze so the images are crisper.
 

pintquaff

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#28
I can still see it with nakered eye ;) hopefully itl be clear again tonight so i can get me scope out (no time las night). if i had a camera mount id take a picture, but i dont ;) might be able to bodge one though...

Dont forget Friday is the big day for the Huygens decent onto titan, will it make any new and inspiring discoveries....
 

elffriend

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I know I am hoping that Huygens will provide us with some spectacular information, but I fear in reality that the whole mission will fail beacuse someone didn't write the correct programme to send the info back, or some piece of equipment on the damn thing will fail.
 

rynner2

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#30
Yee Har!

Finally found thecomet (Machholz) - pretty high, just a fuzzy blob in the bins. Couldn't see a tail though.
 
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