Category Archives: Comets and Asteroids
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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Despite a few previous claims of breaking up or fizzling out (which, technically, was a misquote anyway — it was ‘fizzing’ not ‘fizzling’) it appears that the incoming comet ISON is holding together just fine… although how well it does as it swings closely around the Sun in November has yet to be seen. While it’s not very bright to the naked eye in the night sky yet, ISON is looking pretty good in this new image from Hubble!
There are over 10,000 near-Earth objects (NEOs) that have been identified so far, asteroids and comets of varying sizes that approach the Earth’s orbital distance to within about 28 million miles (45 million km). Of the 10,000 discoveries, roughly 10 percent are larger than six-tenths of a mile (one kilometer) in size – large enough to have disastrous global consequences should one impact the Earth.
This is one of them.
First discovered in February 1950, 1950 DA is a 1.1-km-wide asteroid that was observed for 17 days and then disappeared from view. Then it was spotted again on Dec. 31, 2000 — literally the eve of the 21st century. Coupled with radar observations a few weeks later, in March 2001, it was found that, along with a rather high rotation rate (2.1 hours) asteroid 1950 DA has a trajectory that will bring it very close to Earth on March 16, 2880. How close? Close enough that, within a specific 20-minute window, a collision can not be entirely ruled out.
The image above was made from radar observations by the Arecibo Observatory in Puerto Rico in March 2001, when 1950 DA passed within 7.8 million km of Earth. Are we looking at the mug shot of a future continent-killer?