Category Archives: Comets and Asteroids
This is an article, now updated, that I originally posted in 2009 during my first year of blogging. Since then more research has been done on the famous 1908 Tunguska Event and we even had a remarkably similar type of thing occur in February 2013 over the Chelyabinsk area, not too far from Tunguska, but even today, the 108th anniversary of the event, scientists aren’t in agreement over what it was that violently exploded over the boggy forests of Siberia—asteroid or comet.
Long the subject of debate, with various theories ranging from meteorite impact to a comet to a flying saucer’s sudden engine meltdown, there’s actually strong evidence that the 1908 “Tunguska Event” was likely caused by the explosion of a comet in the upper atmosphere.
This idea has been suggested before, and is supported by Cornell University engineering professor Michael Kelly’s study of – strangely enough – the space shuttle’s exhaust plumes and their effect on high-atmosphere cloud formation.
To those not familiar with the Tunguska Event, something exploded or impacted in the remote area of Russia on June 30, 1908, flattening the forest in an 830-square-mile area, but leaving no visible crater or other obvious sign of what caused the event. Nearby residents reported the sound of a massive explosion, but that’s about it. Whatever it was, the devastation it caused was extensive and undeniable.
ESA’s Philae lander, the first spacecraft to successfully soft-land on the surface of a comet and former piggyback partner to Rosetta, has not been in communication since July of 2015. With 67P now six months past perihelion and heading deeper out into the Solar System and Rosetta’s mission coming to a close this year, it’s not likely that Philae will ever be heard from again.
So now that NASA’s Dawn spacecraft has been in orbit around Ceres for seven months, has the nature of its strange bright spots finally been determined? Are they brilliantly reflective deposits of water ice, as many initially suspected? Or just some curiously-bright rock faces? (Or the metallic remains of an ancient alien space base, like more than a few folks have imagined?) As it turns out, Ceres’ bright spots may be none of these (and especially not that last one… puh-leeze) — they may be enormous deposits of salt.
Ever since we got our first good look at Comet 67P/Churyumov-Gerasimenko from the approaching Rosetta spacecraft in 2014 it has been considered to be a textbook example of a contact binary, with its “rubber duckie” double-lobed shape consisting of an oval “head” and flat-bottomed “body” joined by a “neck.’ Now, using data gathered by Rosetta’s OSIRIS instrument while in permanent orbit, scientists are certain that this is indeed the case: 67P/C-G as we see it today was created by the slow-speed collision of two separate comets, each once an independent and fully-formed object in its own right (and not, as the alternate hypothesis suggested, via the gradual erosion of a once-larger single object.)
Read more about these findings and how they were determined on ESA’s Rosetta site here.
In case you were concerned, there are no large* asteroids, comets, or anything else of a cosmic origin on a destructive collision course with Earth in the foreseeable future – and that most certainly includes this coming September.
On July 29, with ESA’s Rosetta spacecraft in orbital tow, the 2.5-mile (4-kilometer) -long Comet 67P/Churyumov-Gerasimenko fired its brightest jet yet since Rosetta’s arrival just over a full year ago, on Aug. 6, 2014.
Most of the images of 67P showing jets and outgassing activity released over the past few months have been edited to boost jet visibility but this recent flare-up needed no such enhancement. Rosetta’s high-resolution OSIRIS camera had no problem capturing the brief ice capade from 115 miles (186 km) away.