Observations: AstronomyCast Gliese 581

Gliese 581 is a red dwarf star that is located about 20 light years from Earth in the constellation Libra. The mass of this star is estimated to be about one third that of the Sun, and it is the eighty-ninth closest star to the Sun. This red dwarf is particularly interesting because it is one of the most known stars to have a planet that could be hospitable for life. The star has been observed to have six planets in its orbit, two of which may be hospitable for life. Gliese d and Gliese g are the two planets that could be hospitable, with d having the possibility of Earth-like life. However, Gliese g has the greatest likelihood of containing liquid water on its surface. Gliese 581 has been the subject of a huge amount of attention because of these factors. Perhaps these couple of planets surrounding the red dwarf star are the first place to investigate more fully for extraterrestrial life.

Observations: AstronomyCast The Milky Way

The Milky Way is the galaxy that contains the Earth. The Milky Way is a barred spiral galaxy 100,000–120,000 light-years in diameter containing 200–400 billion stars. It may contain at least as many planets, with an estimated 10 billion of those orbiting in the habitable zone of their parent stars. It appears as a flat disk. The Solar System is located within the disk, around two thirds of the way out from the Galactic Center, on the inner edge of a spiral-shaped concentration of gas and dust called the Orion–Cygnus Arm. As a guide to the relative physical scale of the Milky Way, if it were reduced to 100 meters (110 yd) in diameter, the Solar System, including the hypothesized Oort cloud, would be no more than 1 millimeter (0.039 in) in width, or a grain of sand in a sports field. This gives you a real feel for how large the universe truly is. With billions of galaxies in the Universe, our solar system is just a miniscule speck in just one of those billions and bilions of other galaxies. It is very humbling to think about how small one human being is in comparison to our own Milky Way galaxy and the Universe.

APOD 4.8

This is an even more fascinating picture involving water, but this time it is about the water on Jupiter's moon, Europa. Based on the Galileo probe data acquired during its exploration of the Jovian system from 1995 to 2003, Europa possesses a deep, global ocean of liquid water beneath a layer of surface ice. The ice layer plus the ocean underneath could range from 80 to 170 kilometers in depth. Estimating that the average depth is 100 kilometers, Europa would have a condensed ball of water with a radius of 877 kilometers. That's more water than is on Earth! Perhaps Europa is the first place to look for extraterrestrial life in the solar system.

APOD 4.7

This image is very fascinating. When one thinks about the Earth as a whole, they think of a lot of water. 70% of the Earth's surface is covered by water, yet there actually is not that much of it on the planet. Although 70% of the surface seems like a lot, in comparison to the Earth's radius, the oceans are very shallow. If all of the water on Earth was condensed into a ball, the radius of this ball would only be 700 kilometers. That is not even half the size of the Moon. This is an interesting insight into the actual amount of water on this water-planet.

Frank Low Biography

Frank J. Low was born on November 23, 1933 in Mobile Alabama. He grew up in Houston, Texas with his family before attending Yale University to acquire his undergraduate degree in physics. He later returned to Texas to attend Rice University where he would eventually acquire his Doctor of Philosophy in physics in 1959. Low is most famous for his innovation of and work with the infrared telescope. Low worked at Texas Instruments where one of his first assignments was the development of a low-temperature thermometer that was developed using a germanium semiconductor which measured changes in temperature based on the change in the device's electrical resistance as energy was absorbed. Based on his academic experiences, he came to the conclusion that the technology behind this thermometer could be integrated as the basis for a bolometer that could be used to measure the radiant energy coming from stars as infrared radiation. Low went to the National Radio Astronomy Observatory in Green Bank, West Virginia to test his bolometer, which was more sensitive to infrared than detectors previously in use on the Green Bank Telescope. However, infrared waves are absorbed by molecules such as water vapor in the atmosphere. In order to combat this new challenge, Low developed devices that could be attached to aircraft. His most effective device was a twelve inch telescope placed on a Learjet operated by NASA. He later proposed and joined the international project to build the Infrared Astronomy Satellite (IRAS). IRAS was able to discover in excess of 500,000 infrared sources, including many galaxies, and has discovered shells of debris surrounding stars that show the early stages of planetary formation, with debris similar to that later found as the Kuiper belt that encircles our Solar System beyond the orbit of Neptune. Based on these findings, researchers have concluded that the majority of galactic radiation is emitted in the form of infrared radiation that is generated when light from young stars is absorbed by Interstellar dust and then radiated from the dust in the form of heat. Low also worked with NASA on the Spitzer Space Telescope and the James Webb Space Telescope. On June 11, 2009, Low died at age 75. He was survived by his wife, three children, and six grandchildren.

APOD 4.6

This is a picture of one of Saturn's sixty-two moons. This moon is Helene, and this picture was taken by the Cassini spacecraft as it orbited Saturn and reached a distance of only the Earth's atmosphere from Helene. This image has spectacular clarity and will help scientists learn more about the Helene. It could give insight into why the moon appears smooth and streaked as opposed to rough and cratered like our Moon. Helene is also an unusual moon because it orbits Saturn just before Dione, a larger moon, making it one of only four known Saturnian moons to occupy a Lagrange point.