Category Archives: Comets and Asteroids
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.
The more NASA’s Dawn spacecraft observes of the dwarf planet Ceres the weirder it seems to get. Closer investigations of the “bright spots” first seen in Hubble images in 2003 and then in Dawn images upon approach during the first few months of 2015 show an ever-increasing cluster of smaller bright areas (eight at last count) and now a strange lone conical mountain has been found, rising 3 miles (5 km) from Ceres’ surface.
What are the origins of these features? The bright spots are only known at this point to be reflective (rather than light-emitting) substances, and the “great pyramid of Ceres” as it’s being called could be volcanic in origin… but only further investigation will tell.
Dawn will drop down to an altitude three times lower in July, after which much more detailed images will be acquired. What will be discovered then? Stay tuned…
After a brief period of silence (due to its position on the dwarf planet’s night side) NASA’s Dawn spacecraft is now sending back images from orbit around Ceres, revealing amazing details of its surface and giving another look at those mystery “bright spots” that have intrigued scientists since their discovery in 2003.
The animation above shows Ceres’ northern hemisphere as it rotated into the sunlight on April 14. The brightest bright spot can be seen in the crater at right – as Dawn was on approach earlier this year it resolved that spot into two distinct regions.
Scientists still aren’t sure exactly what those are, but soon Dawn will be getting an even better look.