Category Archives: Comets and Asteroids
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.
We all know that Saturn is encircled by a system of rings, and perhaps you also know about the fainter rings around Uranus, Jupiter, and Neptune. But today, ESO astronomers have revealed a surprising discovery: there are also rings surrounding the asteroid 10199 Chariklo, a small, distant world orbiting the Sun far beyond Saturn.
This makes 250-km-wide Chariklo the fifth world ever found to have rings, after the four planets mentioned previously, and, based on the observations, it could also even have its own moon.
“As well as the rings, it’s likely that Chariklo has at least one small moon still waiting to be discovered,” said Felipe Braga-Ribas of the Observatório Nacional/MCTI in Rio de Janeiro who planned the observation campaign and is lead author on the new paper.
Our solar system is an active place, and that is no better illustrated than with these recent observations by the Hubble Space Telescope of asteroid P/2013 R3 breaking apart — and it’s not even disintegrating in Earth’s or any other planet’s atmosphere, but rather as it travels through space 480 million km away from the Sun!
Seen over the course of four months, the breakup of the 200,000-ton space rock is thought to not be the result of an impact event but rather the slight but unyielding force of solar illumination on an already compromised cluster of rubble, barely held together by its own gravity.
“This is a really bizarre thing to observe — we’ve never seen anything like it before,” says co-author Jessica Agarwal of the Max Planck Institute for Solar System Research, Germany. “The break-up could have many different causes, but the Hubble observations are detailed enough that we can actually pinpoint the process responsible.”
What are asteroids made of? While composed of metals, rocks, ices, and also many elements that are difficult to find and retrieve here on Earth — hence the growing interest in asteroid-mining missions — these drifting denizens of the Solar System have many different possible ways of forming. Some may be dense hunks of rock and metal, created during violent collisions and breakups of once-larger bodies, while others may be little more than loose clusters of gravel held together by gravity. Knowing how to determine the makeup of an asteroid is important to astronomers, not only to know its history but also to be better able to predict its behavior as it moves through space, interacting with other bodies — other asteroids, future exploration craft, radiation from the Sun, and potentially (although we hope not!) our own planet Earth.
Now, using the European Southern Observatory’s New Technology Telescope (NTT) researchers have probed the internal structure of the 535-meter-long near-Earth asteroid Itokawa, and found out that different parts have greatly varying densities, possibly an indication of how it — and others like it — formed.
By now you must know about the jets of ice particles blasting out of Saturn’s moon Enceladus, and maybe have even heard about the recent discovery of water vapor issuing forth from Jupiter’s frozen moon Europa. But now we know of another spray-happy world out there: Ceres, which at 591 miles across is our solar system’s smallest dwarf planet but the largest object in the asteroid belt. New findings from ESA’s Herschel Space Observatory reveal that this diminutive world is jetting water vapor out into space, proving both that it has an icy surface and that water does in fact exist in the main asteroid belt, which stretches out between the orbits of Mars and Jupiter. Read more below: Read the rest of this entry
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.
Have you ever seen a meteor streak across the night sky? How about a very bright fireball (aka bolide), one that seemed to disintegrate in front of your eyes or leave a trail of vapor that hung in the air for a few moments? These “shooting stars” are actually tiny bits of rock and dust that exist everywhere in the Solar System, and when they run into Earth’s atmosphere they are slowed down incredibly, resulting in a transfer of energy that releases light and heat — usually enough heat to vaporize the original object entirely. But on occasion a large and/or dense enough object enters the atmosphere and survives the blazing journey to the surface. If it hits land, the meteorite (or its remaining pieces) might one day be discovered by a random traveler, a hiker, a farmer… or a even dedicated “meteorite man” like Geoff Notkin.
Author, educator, and host of Science Channel’s “Meteorite Men” and Cox7′s STEM Journals, Geoff Notkin has dedicated his life to the study, collection, and dealing of these “inert aliens” from outer space. His Tucson-based company, Aerolite Meteorites, sells some of the specimens that he’s traveled around the world to find, and last week I had the chance to talk with Geoff about his business and his passion and learn more about what got him so interested in meteorites to begin with.
“Being a meteorite hunter is probably not the best capital return on your time but it’s a very exciting and rewarding life in every other way.”
– Geoff Notkin, Aerolite Meteorites