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Asteroid #2 down; on to Asteroid #1!
Starts With a BANG! ^ | 8/30/12 | Ethan Siegel

Posted on 09/03/2012 11:44:43 PM PDT by LibWhacker

“I have announced this star as a comet, but since it is not accompanied by any nebulosity and, further, since its movement is so slow and rather uniform, it has occurred to me several times that it might be something better than a comet. But I have been careful not to advance this supposition to the public.” -Giuseppe Piazzi, discoverer of Ceres, the first Asteroid

Out beyond Mars, but not quite out as far as Jupiter, a collection of thousands of rocky objects, ranging in size from pebbles all the way up to the size of Texas, lies the asteroid belt.

Asteroid Belt

Image credit: David Minton and Renu Malhotra.

While the very first asteroid was discovered way back in 1801, with many thinking it was a planet, it was quickly discovered that there were many small, sub-planet-sized objects in between Mars and Jupiter.

Moon with asteriods 1 through 10

Image credit: wikimedia commons users Vystrix Nexoth.

By 1849, there were 10 objects known, with the largest being Ceres and the second largest — at least in terms of mass — being Vesta. As even Ceres is minuscule compared with our Moon (shown in grey, above), none of these objects could rightfully be considered planets, and hence we now consider the entire collection to be the asteroid belt. While the combined mass of every asteroid is just 4% the mass of our Moon, Ceres and Vesta alone are estimated to make up nearly 40% of the mass of the entire belt.

Ceres and Vesta from Hubble

Image credit: NASA, ESA, L.McFadden, J.Y.Li (UMCP), M.Mutchler, Z.Levay (STScI), P.Thomas (Cornell), J.Parker, E.Young (SwRI), C.Russell, B.Schmidt (UCLA).

Because of their small sizes and their incredible distance from us, even these two most massive asteroids — about the size of Texas and Arizona, respectively — barely have any discernable features, even when imaged with the Hubble Space Telescope, as shown above.

But these asteroids are very different from our Solar System’s other rocky worlds. For instance, they’re made up of different elements than we are, their surfaces are very, very old, and they’re the closest things we have lying around to protoplanets: the building blocks of our Solar System’s rocky worlds that haven’t been a part of the inner Solar System in over 4 billion years.

Simulation of the young solar system

Image credit: H. Chang from National Tsing Hua University in Taiwan.

But they are still around in the asteroid belt; Ceres and Vesta are, officially, protoplanets that failed to coalesce into full-on planets. So if we wanted to learn more about the formation of rocky planets in the Universe, that would be the ideal place for a mission. And — wouldn’t you know — we’ve got just such a mission going on right now: say hello to the Dawn Spacecraft!

Dawn in orbit around Vesta

Image credit: NASA.

For over a year, now, Dawn has been in orbit around Vesta, taking more than 28,000 images, mapping the surface in 3-D, and learning more about this distant protoplanet than any such object ever before. Just a visual comparison of Dawn’s true-color composite of Vesta with the one from Hubble should stop you in your tracks.

Vesta from Dawn (L) and Hubble (R)

Images credit -- Dawn view: NASA / JPL / UCLA / MPS / DLR / IDA / color composite by Daniel Macháček; Hubble view: NASA / ESA / STScI / UMd.

There are some amazing features we’ve found on heavily-bombarded Vesta, some of which are completely unique — as far as we know — to our Solar System. Perhaps the most striking is the impact basin over 300 miles (500 km) in diameter on its South Pole, with a mountain over 14 miles high in the center!

Rheasilvia

Image credit: NASA / JPL / UCLA / MPS / DLR / IDA.

Known as Rheasilvia — named after the mother of Remus and Romulus — this crater is 90% the diameter of the entire asteroid, and the wave-like ripples you can see throughout Vesta clearly originated from this impact! Perhaps only two or three other asteroids in the entire belt would have survived an impact like this; all others would have been destroyed.

A false-color topographic map that I’ve managed to track down should really show you just how gigantic this feature is.

Image credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA.

The impact responsible for this also happened relatively late in the Solar System’s history: while most protoplanetary collisions were done more than 4 billion years ago, Dawn discovered that this impact on Vesta happened just 1-to-2 billion years ago, which is very late for the Solar System. The great impact also created this remarkable system of trenches along Vesta’s equator.

Trenches on the equator

Image credit: NASA / JPL / UCLA / MPS / DLR / IDA.

These equatorial trenches are many hundreds of kilometers long, which is gigantic considering the entire asteroid is only some 530 km in diameter! You may also notice that, in addition to the normal light-and-shadows you see over the terrain, there are lots of materials on Vesta that are simply intrinsically dark. You can really see this if you look at the “Snowman” on Vesta.

Vesta's Snowman

Image credit: NASA / JPL / UCLA / MPS / DLR / IDA.

This is still a major mystery: where did this dark material come from? One leading theory is that it came from beneath the surface, and was kicked up unevenly by the impact that created Rheasilvia.

What’s kind of remarkable is that tiny “Vestoids”, or rocks originating from Vesta, were undoubtedly kicked off of the giant asteroid from that impact, and some of them made it to Earth! But back to these three “snowman” craters — Marcia, Calpurnia, and Minucia — we’ve got a true-color image of their interiors as well, and they… well, it’s simply remarkable.

true color of the snowman

Image credit:

Vesta itself is quite rare in many ways: it rotates very rapidly, completing a rotation in less than 6 hours, and it’s inclined both to the ecliptic (at 7 degrees) and on its axis (at 29 degrees), so that there are no permanently shadowed craters. If we could watch Vesta from afar in space, this might be what we’d see.

Rotation of Vesta

Image credit: NASA / JPL-Caltech / UCLA / MPS / DLR / IDA; wikimedia user Little Mountain 5.

And while that might strike you as absolutely amazing — and well, it is – it’s still not the most spectacular thing I’ve got to show you. A huge German collaboration has put together this remarkable flyover sequence of Vesta, complete with explanations of what was discovered, and I can’t do it any better justice than the team has already done. (Full info here.)

[Very cool 5min 20sec YouTube flyover video here]

On the night of September 4th/5th, Dawn will depart Vesta for good to make its way to Ceres, the largest and most massive object in the entire asteroid belt, and will work its magic over there. This is as close as we’ve ever come to understanding the formation of the Solar System and — by extension — the ultimate origins of everything on our world.


TOPICS: Arts/Photography; Astronomy; Science
KEYWORDS: asteroid; asteroids; catastrophism; ceres; dawn; dawnspacecraft; vesta; xplanets

1 posted on 09/03/2012 11:44:48 PM PDT by LibWhacker
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To: LibWhacker

thank you! Fascinating!


2 posted on 09/03/2012 11:57:29 PM PDT by Noob1999 (Loose Lips, Sink Ships)
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To: LibWhacker

Great post. Now all I need is a vestoid to hit me in the noggin before the election.


3 posted on 09/04/2012 1:09:41 AM PDT by MaxMax
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To: LibWhacker

Stunning!
(But, what does this have to do with Muslim outreach?)


4 posted on 09/04/2012 3:09:35 AM PDT by outofsalt ("If History teaches us anything it's that history rarely teaches us anything")
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To: SunkenCiv

I did not know any of this.

Color me a Vesta Virgin.


5 posted on 09/04/2012 3:20:55 AM PDT by martin_fierro (< |:)~)
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To: martin_fierro; LibWhacker; brytlea; cripplecreek; decimon; bigheadfred; KoRn; Grammy; married21; ...

Thanks martin_fierro for the ping, thanks LibWhacker for the topic, an *excellent* ‘extra, extra’ ping for the APoD members (considering that today’s APoD was about hurricanes).


6 posted on 09/04/2012 4:10:44 AM PDT by SunkenCiv (https://secure.freerepublic.com/donate/)
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To: 75thOVI; agrace; aimhigh; Alice in Wonderland; AndrewC; aragorn; aristotleman; Avoiding_Sulla; ...
Thanks LibWhacker for the topic, and thanks martin_fierro for the ping!



7 posted on 09/04/2012 4:13:06 AM PDT by SunkenCiv (https://secure.freerepublic.com/donate/)
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To: KevinDavis; annie laurie; Knitting A Conundrum; Viking2002; Ernest_at_the_Beach; Mmogamer; ...
Thanks LibWhacker for the topic, and thanks martin_fierro for the ping!
 
X-Planets
· join · view topics · view or post blog · bookmark · post new topic · subscribe ·
Google news searches: exoplanet · exosolar · extrasolar ·

8 posted on 09/04/2012 4:13:13 AM PDT by SunkenCiv (https://secure.freerepublic.com/donate/)
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To: LibWhacker

That color photgraph of those craters, if it’s “true color” suggests that the bluish colored features may consist of copper oxide or some cyanate perhaps...in which case there was sometype of water and oxygen exposure to this rock at somepoint or other...perhaps high heat during an ice comet impact.


9 posted on 09/04/2012 4:13:51 AM PDT by mdmathis6 (Not left wing! Not right wing! But....CHRIST WING!)
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To: SunkenCiv
A lifeless, dead piece of amazing opportunity to mine and use for our benefit. Space exploration is not worthless. That is all.
10 posted on 09/04/2012 4:20:09 AM PDT by VaRepublican (I would propagate taglines but I don't know how. But bloggers do.)
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To: LibWhacker

Wonderful! Thank You!


11 posted on 09/04/2012 4:48:29 AM PDT by left that other site (Worry is the Darkroom that Develops Negatives.)
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To: LibWhacker

Super kewl!


12 posted on 09/04/2012 5:04:08 AM PDT by Lonesome in Massachussets (The Democratic Party strongly supports full civil rights for necro-Americans!)
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To: martin_fierro

Actually, you could call yourself a “Vestal Virgin.” In ancient Roman religion, the Vestals or Vestal Virgins (Vestales, singular Vestalis), were priestesses of Vesta, goddess of the hearth.

http://en.wikipedia.org/wiki/Vestal_Virgin

BTW, Ceres is named for Ceres, goddess of agriculture, grain crops, fertility and motherly relationships and the matron saint of Sicily, site of her discovery.


13 posted on 09/04/2012 5:08:33 AM PDT by Lonesome in Massachussets (The Democratic Party strongly supports full civil rights for necro-Americans!)
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To: LibWhacker; Lonesome in Massachussets; SunkenCiv

They should've named all three of these "Marcia."

why does nobody listen

14 posted on 09/04/2012 7:11:42 AM PDT by martin_fierro (< |:)~)
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To: VaRepublican
A lifeless, dead piece of amazing opportunity to mine and use for our benefit. Space exploration is not worthless. That is all.

The earth's crust contains some 15% iron while many asteroids are believed to contain as much as 70% iron. The moon is covered with titanium and aluminum oxides.
15 posted on 09/04/2012 7:14:26 AM PDT by cripplecreek (What does it profit a man if he gains the whole world but loses his soul?)
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To: outofsalt

It is a place to send them.


16 posted on 09/04/2012 7:18:13 AM PDT by bmwcyle (Corollary - Electing the same person over and over and expecting a different outcome is insanity)
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To: LibWhacker

All the grooves out there have intrigued me since Voyager.


17 posted on 09/04/2012 8:14:17 AM PDT by BenLurkin (This is not a statement of fact. It is either opinion or satire; or both)
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To: BenLurkin

Probably some woman tried to park the damn thing.............


18 posted on 09/04/2012 11:29:25 AM PDT by doorgunner69
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