Comet Siding Spring won’t hit Mars on October 19 but it will come really, really close: 86,000 miles, or just a bit over 1/3 the distance between the Moon and Earth. That’s like having a bullet from a sniper positioned a mile away knock your hat off! (Given that you were the target of a military-class sniper, not sure why you would be. Is there something I don’t know about you?) And while it won’t get bright enough or close enough to Earth to become a spectacle in our night sky, exploration robots on and around Mars should be in for quite a show.
Earlier this month, as Siding Spring (aka C/2013 A1) passed within the orbit of Jupiter, the Hubble Space Telescope turned its gaze onto it and captured the image above showing the comet’s icy 12,000-mile-wide coma and, after some processing, what appear to be two strong jets spraying out of its as-yet-unseen nucleus. These observations — and more like them in the months to come — will help scientists determine Siding Spring’s motion and rotation rate and what sort of interaction Mars (and its resident robots) can expect from its ejected material this fall.
It’s being called “the most important alarm clock in the solar system” — tomorrow, Monday January 20, at 10:00 GMT (which is 5:00 a.m. for U.S. East Coasters like me) the wake-up call will ring for ESA’s Rosetta spacecraft, bringing it out of hibernation after over two and a half years in preparation of its long-awaited rendezvous with a comet later this year.
The signal will incite the warming of Rosetta’s star trackers, which allow it to determine its orientation in space. Six hours later its thrusters will fire to stop its slow rotation and ensure that its solar arrays are receiving the right amount of sunlight. Using its thawed-out star trackers Rosetta will aim its transmitter towards Earth and, from 500 million miles (807 million km) away, will send a thumbs-up message that everything is OK and it’s time to get to work.
From that distance the transmission will take 45 minutes to reach us. Rosetta’s first signal is expected between 17:30 – 18:30 GMT (12:30 – 1:30 p.m. ET).
And, if all is well, Rosetta has a very exciting year ahead! Read the rest of this article here.
UPDATE Jan. 20: Rosetta has awoken! This afternoon at 18:18 UTC, after 48 minutes of increasingly tense anticipation, a signal was received from the spacecraft by both NASA’s Deep Space Network in Goldstone, CA and the ground station in Canberra, Australia. Rosetta is up and running and so far seems to be in good condition — Go Rosetta and Philae! Read the full story from ESA here.
Yesterday sure was interesting. As the astronomical world, from scientists to journalists to enthusiasts alike, watched online in near real time as ISON came within its closest pass of the Sun — in literally ever — the comet, having spent the previous several hours brightening steadily, suddenly went dim as it traveled deep into the Sun’s outer corona. It appeared that it had fallen apart, disintegrating* into a smear of bright particles just as it began to round the Sun. Even as astronomers looked to spot a sungrazing ISON in several of NASA’s Solar Dynamics Observatory’s imaging fields, nothing was to be found, leading many to pronounce the billion-year-old icy visitor from the Oort Cloud dead on arrival.
But then, just as the Twitterverse was lamenting the loss of this year’s most famous comet, something reappeared… and even now, a full day later, they’re still not quite sure what.
Unless you’ve been living in the Oort Cloud you’ve probably heard about the current travels of comet C/2012 S1 (aka ISON) through the inner solar system. Although this soon-to-be “sungrazing” comet was first spotted by astronomers Vitali Nevski (from Belarus) and Artyom Novichonok (Russia) on Sept. 21, 2012, it’s actually been on its way toward the Sun for much, much longer — possibly for the past several million years or so. But on November 28 at 1:38 p.m. EST, as many Americans are sitting down for their Thanksgiving Day dinners here in the U.S., ISON will make its closest pass around the Sun (called perihelion) and, while you won’t be able to see it in the sky at that point (it’s much too close to the Sun right now) our many eyes in the sky will be watching.
There’s been a lot of misinformation passed around the ‘net recently regarding ISON (as seems to be de rigueur whenever something astronomical is occurring) and I can’t stress enough that there’s no reason to be concerned about this comet’s visit. If anything, ISON should be the one worried — there’s still a chance that it won’t survive perihelion intact! In fact, some reports are suggesting that it already has broken up (which as yet has not been confirmed). So to answer some of the most common questions people have been asking about ISON, NASA has shared some video interviews with experts on the subject. Watch them below:
While many skywatchers, scientists, and astronomy enthusiasts around the world wait to see if comet ISON survives its perihelion — that is, its closest pass by the Sun — on Nov. 28, the MESSENGER spacecraft has captured an image of the incoming comet from its position in orbit around Mercury!
The image above, shared today on the MESSENGER website, shows ISON from a distance of 22.5 million miles, and just over 42 million miles from the Sun. At perihelion ISON will come within a scant 730,000 miles of the Sun. Whether or not it survives its Thanksgiving Day encounter has yet to be seen.
If you thought tails were just for comets and cats, this asteroid is about to prove you wrong.
On August 27 astronomers spotted an unusually fuzzy looking object in survey images taken with the Pan-STARRS telescope in Hawaii. The multiple tails were discovered in Hubble images taken on September 10, 2013. When Hubble returned to the asteroid two weeks later, its appearance had totally changed — it looked as if the entire structure had swung around!
While this object is on an asteroid-like orbit, it looks like a comet, and is sending out tails of dust into space. Because nothing like this has ever been seen before, astronomers are scratching their heads to find an adequate explanation for its mysterious appearance.
Every few days or so I like to check the “Close Approaches” page of JPL’s Near-Earth Object Program, just to see what sorts of cosmic objects are whizzing by our planet; how big they are, when they’ll come, and how far they’ll (hopefully!) miss us by. Most of them are relatively small asteroids several dozen meters in width, passing us at a few tens of lunar distances (avg. distance to the Moon is about 370,000 km/235,000 miles or so.) Every now and then, though, something passes us by closely, coming within a handful of lunar distances — or even closer than the Moon itself. These events spark my interest as they remind us that there’s a lot of bits of solar system out there, and sometimes (while we’re busy doing other things) the bigger pieces get unnervingly close.
Yesterday JPL’s NEO specialists Don Yeomans and Paul Chodas posted an article about some “surprising discoveries” of three recently-found asteroids — all of which are of considerable size (two ~19 km/12 miles wide and one 2 km) and the third of which passes by closely enough to be considered “potentially hazardous” (as opposed to merely “near Earth”). Curious? Read on…
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