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New Moon System Around Uranus
An anonymous reader writes "Astronomers have discovered two of the smallest moons yet found around Uranus. The new moons, uncovered by NASA's Hubble Space Telescope, are about 8 to 10 miles across (12 to 16 km) -- about the size of San Francisco. The two moons are so faint they eluded detection by the Voyager 2 spacecraft, which discovered 10 small satellites when it flew by the gas giant planet in 1986. The newly detected moons are orbiting even closer to the planet than the five major Uranian satellites, which are several hundred miles wide. The two new satellites are the first inner moons of Uranus discovered from an Earth-based telescope in more than 50 years. "It's a testament to how much our Earth-based instruments have improved in 20 plus years that we can now see such faint objects 1.7 billion miles (2.8 billion km) away," says Mark Showalter, a senior research associate at Stanford University. 'The inner swarm of 13 satellites is unlike any other system of planetary moons,' says co-investigator Jack Lissauer. 'The larger moons must be gravitationally perturbing the smaller moons. The region is so crowded that these moons could be gravitationally unstable. So, we are trying to understand how the moons can coexist with each other.'"
Although the new moons are large in terms I can understand, they seem very, very small when comparing them to planets.
Is there a definition of a moon? Must something be X miles/kilomters in size or volume?
If these moons are gravitationally astatic, stochastic motion could account for their motion in this deterministic system. We all know how complication three-body motion is, so with the number of objects affected by various gravitational fields out there, it would be incredibly hard to predict any movement at all. I wish them good luck in trying to precisely "understand how the moons can coexist with each other".
Is it not possible that these moons are so unstable that they will have relatively short lifespans? Might they soon end up crashing into the planet's surface or interact together and get flung off out of the solar system?
Turkeyphant
...so eager to take Hubble down, when it's still contributing so much to astrophysics? The new space telescope isn't even ready for launch yet, and who knows if it will work at first go? I'd rather have Hubble as backup until the new one is working smoothly and flawlessly before even thinking about bringing it down. Capitalism and politics just don't mix well with science.
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The new moons, uncovered by NASA's Hubble Space Telescope, are about 8 to 10 miles across (12 to 16 km) -- about the size of San Francisco.
The two new satellites are the first inner moons of Uranus discovered from an Earth-based telescope in more than 50 years. "It's a testament to how much our Earth-based instruments have improved in 20 plus years that we can now see such faint objects 1.7 billion miles (2.8 billion km) away," says Mark Showalter.
Is Hubble considered an Earth-based telescope somehow? I'm kind of confused. Can anyone explain this?
Pardon my ignorance, but I thought that Jupiter and Saturn were the only true Gas Giants, and Uranus wasn't (irrespective of composition). Then again, I am not an Astronomer, so I could be wrong here. This seems pretty impressive for the Hubble, who knows whether it would have found them earlier if the optics had worked from day one?
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The small moons are probably fragments knocked off one of the larger moons and may be in descending spiral orbits. If they are permanent, then I would suspect that they would be in some sort of synchonicity with the larger moons, using the gravitation to help maintain a stable orbit (if they were not synchroeous they would be unstable, IIRC)
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Uranus is not the only planet that spins on its side. It's equtorial inclination to orbit is 98 degrees. Pluto(in my opinion not worth of being called planet) has an angle of 122 degrees qutorial inclination to orbit. Venus is bizzare with an equtorial inclination to orbit of 177.4 degrees. Another ineresting fact about Uranus is that it was accidentally discovered in 1781 by the British astronomer Sir William Herschel and was originally named the Georgium Sidus (Star of George) Here are other facts about Uranus. http://kvtr.elte.hu/tnp/nineplanets/uranus.html
"Most interesting how often you humans seem to obtain that which you do not want" -Spock
There are entirly too many moons. In the case of Uranus we will soon need more female Shakspearian characters to name them after.
"Most interesting how often you humans seem to obtain that which you do not want" -Spock
The time on the Hubble is FREE from STSI (Space Telescope Science Institute, in Baltimore MD) NASA pays them to operate HST, as a scientist you just have to submit a good experiment to STSI, get approved and wait in line for years for your observation. If the HST is down or croaks during your observation window, too bad, you go back to the end of the line and wait. Hubble will soon be upgraded (SM4) to have better "eyes" when the Shuttle is back up. I have worked some on the SM4 software, its a LOT of very very old C code on an old 286 processor, plus some one of a kind processors from 25 yrs ago that no one else but NASA uses. Several of the instruments have NO software. But it gets the job done. If Uranas has the two Moons, I would have thought HST would have found them by now as they DO look at the planets and not just the neato nifty nebulas and stuff sveral Sagans ("billions and billions") of light years away
JWST (James Web Space Telescope) is just now reaching the requirements definition phase, expect 7-10 yrs before launch. It will be stationed at L-4 or L-2 (the Earth Sun Lagrange Points where the gravity pull of the Earth and Sun are equal, so the object kinda just sits there with very litte station keeping needed) which is a LONG way from Earth, so the JWST better work right the FIRST time cuz there ain't no way to get there to put glasses on it!
Any other questions?