Earth at Night
Take a good look at this picture. The white spots are NOT snow. They’re light pollution. That’s right. This is the home of a species that is so wealthy that it can afford to waste megawatts of power by splashing it up into the sky. This picture says that the civilization living here has conquered ALL the problems of poverty, hunger, and housing because it has money to burn sending light into space.
In reality, this is the home of a species that fights over energy, has extremely poor people who are starving to death while others can afford to flaunt their wealth in dazzling displays of light.
Pity isn’t it? You know why? Because those Earth lights are obscuring our view of the universe of which we are a part. I suppose it’s too much to ask that we figure out ways to conserve our energy use so that humanity can once again connect with the cosmos that gave it birth. Seems like a civilized thing to do, don’t you think?
Want to fight light pollution?
The International Dark-Sky Association (IDA) is a leader in the wise use of lighting. Check out their handy informational sheets about proper light usage and how it can save the environment and money!
A spectrum showing lithium in a metal-poor star
Not all the great stuff astronomers get the from sky is in the form of pretty pictures. Granted, gorgeous astrophotos are addictive, but they don’t tell the whole story of the universe. Astronomers also study data in the form of spectra. The figure above is a good example of a spectrum. Basically it tells astronomers that a star called G271-162 has a certain amount of an element called “lithium” — which is relatively rare in the cosmos compared to other elements. This star is what is known as a “metal-poor” star — one that formed in the earliest times of the universe. “Metal-rich” stars are those formed from interstellar gas and dust that has probably been “recycled” through at least one star and enriched with metals. So, if we study older stars like G271-162 and figure out how much they have of certain elements, that will tell us a lot about what elements were most plentiful in the early, early universe. Astronomers want to understand how much lithium was produced in the birth of the universe — the Big Bang — some 12 to 14 billion years ago. The amount of lithium older star will help them understand it.
You can’t take a picture of lithium, but you can study the light coming from a star — and break it up into a spectrum. If lithium is present in the star, it will show as a “dip” in the spectral line — which is exactly what you see in this graph.