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Objects in space are rather far away. The Moon is our closest celestial neighbor at nearly a quarter million miles from Earth, and the nearest star, our Sun, is 93 million miles away.
These extreme distances mean that it’s usually impossible to touch real objects in space (meteorites that fall to the ground not withstanding). Advances in both astronomy and technology, however, now allow you to do the next best thing: hold a 3-D model of one based on real data.
Cassiopeia A is located about 10,000 light years from Earth. How does that compare with our local cosmic objects of the Sun and Moon? One light year equals the distance that light travels in a year, or just under 6 trillion miles (~10 trillion km). This means that Cassiopeia A is an impressive 60,000,000,000,000,000 miles (100,000,000,000,000,000 km) from Earth. But since it’s in our Milky Way, it’s in our cosmic back yard, so to speak.
The story behind such a remarkable feat starts with how astronomers study space. Unlike previous generations of sky gazers, today’s astronomers look at the Universe in many kinds of light, across the full electromagnetic spectrum. Through advanced telescopes and detectors, scientists can “see” from radio waves to gamma rays. Why is this important? We need to look at the Universe in all the types of lights to even begin to understand it.
Take X-rays, for example. Back in 1999, NASA’s Chandra X-ray Observatory was launched in order to observe the high-energy Universe including such things as colliding galaxies, black holes, and supernova remnants.
One such supernova remnant that Chandra studies is Cassiopeia A. About 400 years ago, in our own Milky Way galaxy, a star that was about 15 to 20 times the mass of our Sun, detonated in a supernova explosion.