We Really Are Stardust

Where did human life come from? That's the ultimate question. Science offers two solutions to this question. One is that life was placed here either by an intelligent being, or by chance via a meteorite back when the Earth was very young. The second option is that space is filled with the building blocks of life, and the gas and dust that the Earth formed from happened to contain these materials. Until now there was really no strong proof either way, but just recently astronomers made a huge discovery. Astrobiologists were studying the composition of a meteorite they found in the arctic and discovered guanine and adenine, two of the four building blocks of DNA! These proteins have never been found in outer space before, and astronomers believed conditions to be too harsh for these proteins to survive. Finding guanine and adenine in this meteorite suggests that these and other building block of DNA are created during supernova explosions and exists all throughout outer space. It's likely that these materials existed in the circumstellar disk around the sun back when it was very young, and therefore ended up here on Earth.  This also promotes the idea that other intelligent life may be out there since the building blocks for life seem to be free floating through space. There are of course religious based views on the formation of life, which I respect very much, but from a purely scientific standpoint, it appears that we really are a product of the stars.

Image Credit: NASA
Go to NASA.gov to read the article pertaining to this discovery.

Star Trails

 

 Images like the one above are often taken by artistic astronomers and are called star trails. Stars, just like the sun and moon, rise and set every night due to the rotation of the Earth. These pictures show the path in which stars move across the sky over a single night.  To image star trails, you either need to leave the shutter open on your camera all night and take one long picture, or take hundreds of images  all night long and stack them together. Notice in the image above that many stars appear to rise above the horizon on the east and set on the west, but some move in a full circle and never rise or set. These stars are called circumpolar stars. Imagine you are standing at the tip of the North pole and looking up at the stars. All of the stars would appear circumpolar because you are standing on the tip of Earth's spin axis (also called the north celestial pole). Now if you move down to North America you'll be on the side of Earth's spin axis, and only some stars (those in the direction of the north celestial pole) will appear circumpolar. Similarly, if you are at the equator (middle of earth) there will be no circumpolar stars, because the north and south celestial poles sit exactly on the horizon. Based on images of these star trails you could measure the exact latitude of your location on Earth.