Earth gets bombarded from space all the time. With all the micrometeorites, not to mention the occasional meteor or comet, almost 50 tons of material falls to Earth every day. Since all this material from space reaches Earth, you might think that interstellar material falls to our planet all the time. But it turns out that isn’t the case. The vast majority of material comes from within our solar system. Even cometary material comes from the Oort cloud at best, and that’s still on the outer edge of our solar system. There is plenty of interstellar gas and dust beyond our solar system, but even when some of it heads our way it tends to be pushed away from the inner solar system by the solar wind. So we haven’t had any samples of interstellar dust to study.
Media Day
[av_video src=’http://youtu.be/ndS3kIWrjk8′ format=’16-9′ width=’16’ height=’9′] This morning a Universe Today video on the size of the universe was released, which I helped write. Then in the afternoon I was on Connections with Evan Dawson, where we talked about the latest news about the comet Churyumov-Gerasimenko, science communication and a range of other astronomical topics. You can check out that interview here. For those …
Night of the Comet
The Rosetta spacecraft has successfully moved into orbit around 67P/Churyumov-Gerasimenko. We’ve been getting images of the comet as Rosetta approached, but now that it’s in orbit we are getting high resolution images such as the one above. You’ll notice the comet really looks like an asteroid, with what seems to be a rocky/dusty surface. That’s because comets and asteroids aren’t as different as often portrayed.
Mars Mission
On October 19 of this year the comet C/2013 A1 (more commonly known as Siding Spring) will make a very close approach to Mars. At its closest point, the comet could be only 120,000 km from the surface of Mars. There’s no chance it will hit the planet, but such a near miss could have an effect on both the planet and the probes orbiting it.
On the Rocks
We generally think of comets and asteroids as two distinct types of bodies. Comets are “dirty snowballs” of mostly ice, which vaporizes to form long tails when they approach the Sun, while asteroids are dry, rocky bodies that typically live in the asteroid belt. It is generally true that comets tend to have an icy surface of volatiles that can evaporate off its surface, and asteroids generally don’t. But it also turns out that the two are far more similar than they are different.
To Greet the Morning Sun
Comets are often pictured as cold objects, far from the Sun, but in fact there are many comets that approach quite close to the Sun, such as the one pictured above. They are known as sungrazers, and they have an interesting story to tell.
Signs and Portents
In 1066 a comet appeared in the sky, larger than Venus, and unusually bright. Like many comets, its appearance was taken as an omen. This happened to be the same year as the Battle of Hastings, in which the Anglo-Saxon King Harold II clashed with Duke William II of Normandy in a battle which sealed the Norman conquest of England. After the battle it became clear that the comet was an omen of William the Conqueror’s victory, which is commemorated in the Bayeux Tapestry. The comet is included in the tapestry, as you can see.
Good to be the King
Jupiter is sometimes said to be a failed star, with a mass just a bit too small to fuse elements in its core. This isn’t really an accurate description, since the it takes at least 13 times the mass of Jupiter to initiate fusion. However, when compared to the other planets in the solar system, Jupiter is king. Jupiter is 2.5 times the mass of all the other planets combined.
Out of Beta
Observations from the ALMA telescope array has made some interesting observations of carbon monoxide in the vicinity of the star Beta Pictoris. The results have been published recently in Science, and it tells an interesting story about comets and planetary formation.