Page 24 - Life beyond the Karman

COLLIDING GALAXIES
Neighbouring galaxies sometimes drift close enough for the force of gravity to make them collide. Flying to each other at millions of kilometres per hour, they crash in a blaze of fireworks as colliding gas clouds give birth to thousands of new stars. Sometimes the collision slows down the movement of the galaxies so much that a second or third pass through happens. In time, the two galaxies may merge to form one larger galaxy.
Oddball galaxies
Astronomers discovered that many of these oddities are the results of collisions, mergers, or other interactions between two or more galaxies.
Oddball galaxies include:
• Cartwheel galaxy;
• The porpoise;
• Antennae galaxies.
GALAXY CLUSTERS Andromeda Galaxy
Andromeda, which is the nearest large galaxy to Earth, is a great spiral galaxy. It is one of the few galaxies that are visible to the unaided eye, appearing as a milky blur. Located about 2,480,000 light-years from Earth; its diameter is approximately 200,000 light-years; and it shares various characteristics with the Milky Way system.
Triangulum, pinwheel or M33
The Triangulum Galaxy is a beautiful large face-on spiral galaxy located in the constellation of Triangulum. Also known as NGC 598, and the Pinwheel Galaxy, M33 was first discovered more than 350 years ago by Hodierna and re-discovered by comet- hunter Charles Messier in 1764.
M33 is part of our local cluster of galaxies, including our own
Milky Way galaxy, M31, and the Magellanic Clouds. This cluster is also part of a much larger super-cluster of galaxies called the Virgo cluster. M33 covers an apparent area of sky bigger than the full moon, but it also has relatively low surface brightness.
Nebula
A nebula is a giant cloud of dust and gas in space, mostly hydrogen and helium. Some nebulae (more than one nebula) come from the gas and dust thrown out by the explosion of a dying star, such as a supernova. Others are regions where new stars are beginning to form.
The dust and gases in a nebula are very spread out, but gravity can slowly begin to pull together clumps of dust and gas. As these clumps get bigger and bigger, their gravity becomes stronger and stronger. Eventually, the clump of dust and gas gets so big that it collapses from its own gravity. This causes the material at the centre of the cloud to heat up and the hot core is the beginning of a star.
22
LIFE BEYOND THE KÁRMÁN LINE - OUTER SPACE