5. This image shows a small portion of a nebula called the "Cygnus Loop." This
supernova remnant lies 2,500 light-years away in the constellation Cygnus the
Swan. (Courtesy of Jeff Hester (Arizona State University) and NASA)
6. This is an image of the Crab Nebula, a supernova remnant
6,000 light years away. Copyright Association of
Universities for Research in Astronomy Inc. (AURA)
7. What is a light year?
A light-year is a unit of distance. It is the
distance that light can travel in one year.
Light moves at a velocity of about 300,000
kilometers (km) each second. So in one
year, it can travel about 10 trillion km. More
precisely, one light-year is equal to
9,500,000,000,000 kilometers
(5,890,000,000,000 miles)
8. This is the Vela Supernova Remnant. This nebula is the remnant of a
supernova that exploded about 10,000 years ago.