What are the odds that an asteroid impact will injure people?
Quasicrystals are usually made in the lab, but they can also form in the asteroid belt.
Euphrosyne is the 5th most massive asteroid in the solar system. It has the highest density of any asteroid, so it’s only the 12th largest in terms of diameter. Despite its size, however, we actually don’t know that much about Euphrosyne.
Observations of a white dwarf finds evidence of a Ceres-sized asteroid comprised of one third water.
The Japanese spacecraft Hayabusa 2 has launched successfully, and is on its way to the asteroid 1999 JU3. The mission is the successor to the first Hayabusa mission, which landed on the asteroid 25143 Itokawa, and returned dust particles from the asteroid to Earth. This new mission will also strive to return samples to Earth, but it is also more ambitious. The …
All large asteroids have been bombarded over the ages, and as a result smaller chunks have been cast adrift in the solar system. Some of these smaller bits fall to Earth as meteorites. One of the things we notice about meteorites is that many of them have certain similarities of composition and chemical signature. As a result they can be identified into groups. This would imply that these groups have a common origin, likely a particular asteroid.
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.
The Rosetta spacecraft is on its way to an asteroid known as 67P/Churyumov–Gerasimenko. In August it will go into orbit around the asteroid, and then in November it will put a lander known as Philae on the rock. The surface gravity of this asteroid is less than 1/20 that of Earth, so Philae will actually have harpoons to keep it attached to the asteroid. It’s an ambitious mission, since unlike many landings we have no idea what the surface of the asteroid will be like. In fact until recently, we weren’t entirely sure what the shape of 67P/Churyumov–Gerasimenko actually is.
We generally think of asteroids as looking like gray rocks. While that’s true to our limited eyes, more sensitive instruments find they have a variety of colors. You can see an example of this in the image above of the asteroid Vesta. This false color image was made by observing Vesta at various wavelengths in the visible and infrared spectrum. It shows that Vesta has variations in color too subtle for us to see with our eyes.
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