Experimental Blog # 123

Notes and such from "Space Chronicles" - Facing the Ultimate Frontier by Neil deGrasse Tyson and edited by Avis Lang

The author, Neil deGrasse Tyson, points out that both he and NASA, the National Aeronautics and Space Agency, were "born" in the same year, 1958.
Among many interesting facts in this book are:

Hydrogen, helium, oxygen, carbon, and nitrogen are the 5 most common elements in the universe and, except for helium, which is not chemically reactive, the other 4 are also the most common elements of life, including people. So, we indeed are very much a natural product of the universe.

The Earth now has hundreds of communication satellites and 12 space telescopes. Hubble, which was launched in 1990, is the most well known, and, hopefully, will soon be replaced by the even more powerful James Webb Space Telescope.
The International Space Station is located in a low Earth orbit about 225 miles above the Earth.
In most cases it is "vastly cheaper to send robots" into space than people; usually about a fiftieth of the cost.

There are 5 "Lagrangian points" around the Earth-Moon system "where the gravity of Earth, the gravity of the Moon, and the centrifugal forces of the rotating system all balance."
There are also 5 such points around the Earth-Sun system, and it is planned that the James Webb Space Telescope will be placed in one of them.
There are thousands of asteroids gathered at 2 of the Lagrangian points in the Sun-Jupiter system, and there is other "space junk" in the Sun-Earth and Earth-Moon systems as well.

However,  "On Friday the 13th, April 2029, an asteroid large enough to fill the Rose Bowl as though it were an egg cup will fly so close to Earth that it will dip below the altitude of our communications satellites. ... If the trajectory of Apophis{the asteroid} at close approach passes within a narrow range of altitudes called the "keyhole," then the influence of Earth's gravity on its orbit will guarantee that seven years later, in 2036, on its next trip around, the asteroid will hit Earth directly, likely slamming into the Pacific Ocean between California and Hawaii. ... If Apophis misses the keyhole in 2029, we will have nothing to worry about in 2036."