Tuesday, April 5, 2011

Galactic Cannibalism!

 Galactic cannibalism…. Just the name must intrigue you!





If two galaxies traveling through outer space happen to pass close enough to each other they will interact. Often they will be "nice" and just push and tug on each other a little bit, distorting their shapes.  But sometimes galaxies pass so close that they collide and consume one  another! The system above is a real Hubble Space telescope image of the whirlpool galaxy system. The galaxy on the left, and  what's left of the galaxy on the right collided a short time ago. The left galaxy was initially larger and has a larger black hole at it's center than the right one. Because of this, the left galaxy is slowly "eating" the right galaxy by stripping off all of the right galaxy's gas, dust, and stars. A true example of galactic cannibalism!

Did you know that our own galaxy, the Milky Way, expects the suffer the same fate? We are on a high speed collision course with our neighboring (and much larger) galaxy, Andromeda. When we finally collide, Andromeda is expected to cannibalize us! But don't get too worried, even though we are hurtling towards each other at 80 miles/second (yes, I mean per second!), we have about 3 billion years before the collision actually occurs. Phew!

Image Credit: NASA/HST

Sunday, April 3, 2011

The Surface of Mercury

It's taken more than 6 years, but MESSENGER has finally made it into Mercury's orbit!

 
The MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER) Space Probe was launched in 2004, with the purpose of studying the composition and magnetic field of the closest planet to our sun. Sending a probe to Mercury is not as easy as you might think. We can't just aim a rocket towards mercury and let the probe go; it would pass right on by Mercury and get swallowed by the sun. Instead, we must aim it such that the probe will make multiple orbits around the sun, each one honing closer into mercury's orbit. MESSENGER had to make 7 (I believe) orbits around the sun before it made it was captured by Mercury's gravitational field. The very first image send back from MESSENGER in Mercury's orbit is shown above. Mercury looks much like the moon; a small rocky body that's been bombarded by craters for years! MESSENGER plans to sends tons of pictures of Mercury back to Earth, so stay tuned for even more awesome shots of this little planet!

Image Credit:NASA/JHU APL/CIW