APOD 2.5 The Magnificent Tail of Comet McNaught

In 2007, Comet McNaught became the brightest comet to streak across the sky in the last 40 years and the second brightest since 1935. The comet was visible in the Southern Hemisphere. In the Northern Hemisphere, the tail of the comet was visible right after sunset. The tail was measured to be about 35 degrees in length at its peak. This image, taken by the discoverer of the comet, was captured in Australia in 2007 after sunset and the comet reached an apparent magnitude of -6. For comparison, Venus' maximum brightness is at an apparent magnitude of -4.6 and the full moon has an apparent magnitude of -12.6. The head of the comet was extremely bright and was even visible to some observers in cities in the Southern Hemisphere. The Ulysses spacecraft, which was designed to study the sun, encountered the tail of Comet McNaught.

APOD 2.4 Bright Sun and Crescent Earth from the Space Station

This stunning view of the Earth and the Sun was taken from the International Space Station during its rendezvous with the Space Shuttle Atlantis. Atlantis was launched from Cape Canaveral, Florida on November 16th, and returned home on November 27th. The point of the mission was mainly to send spare parts, to repair, and to build upon the ISS. The mission, STS-129, lasted 10 days. As the International Space Station and the shuttle separated for Atlantis' trek home, they were visible streaking across the sky multiple nights in a row. In the image, the Sun is very bright, and a small crescent of Earth is visible that is still in the sun's light. This crescent is a result of the ISS' orbit around the Earth. A long solar panel extends from the ISS and collects the light from the sun in order to keep the space station functioning. This image captures the beauty of the Earth that many people forget about when they go through their life.

Observations

Date: 12/1/09

Time: 8:35-8:50

Conditions: Clear everywhere except in the East, which had cloud cover low, near the horizon. Not many objects visible because it was slightly hazy.

Observations:

Moon: Full, about 30 degrees high in the East. Could see a small halo when clouds passed in front of the moon.

Jupiter: very bright with a haze in front of it. About 17 degrees high.

Capella: About 12.5 degrees of angular separation from the moon, located in the Northeast.

Fomalhaut: in the constellation Pisces Austrinus in the SSW, dim compared to normal.

Andromeda high overhead

Cassiopeia: high over head, slightly oriented to the North. Could not see all the stars of the WorM asterism.

Observations

Date: 11/26/09

Time: 6:35-6:50

Location: Venice, FL

Conditions: Clear

Moon: Waxing Gibbous, high in the SouthEast

At 6:43, in the NNW, the ISS streaked across the sky for about two minutes. About 15 seconds after the ISS appeared, the Space Shuttle Atlantis transited the sky in the same direction. The two were at an angular separation of a few degrees. Both were very bright.

Date: 11/27/09

Time: 7:00-7:15

Location: Venice, FL

Conditions: some clouds, but bright stars still visible

Moon: Waxing Crescent, high in the SouthEast

At 7:06, the ISS again crossed the sky for about two minutes, this time in the WNW. The ISS was very bright.

Apod 2.3 Water Discovered in Moon Shadow

Last month, NASA sent a projectile to crash into the moon. The project was called the LCROSS mission. As part of the mission, one projectile crashed into the moon, followed by another that carried a detector. The detector's purpose was to see if there were signs of water on the moon. The impact occurred in a permanently shadowed crater on the moon's south pole. This past week, results from the chemical analysis of the dust plume showed clear evidence of water. The source of the water is unknown and is the topic of much debate. Whether from a small meteorite, a comet, or from primordial moon soil, the water is a mystery. The water is important because it could help us understand the history of the moon and could be the source of water that would allow astronauts to live on the moon for an extended period of time. NASA has plans to build a lunar colony somewhere between 2019 and 2024, so the presence of water is a big step in the fulfillment of these plans.

APOD 2.2 Stickney Crater

Stickney Crater is the largest crater on the tiny moon, Phobos, which orbits Mars. The crater, almost 9 kilometers from side to side, is almost half the diameter of Phobos itself. The crater is named after the wife, Chloe Angeline Stickney Hall, of Asaph Hall, who discovered Mars' two moons in 1887. The impact that formed this crater most likely cam very close to shattering the minuscule Martian satellite. This picture was captured by the HiRISE camera, which is part of the Mars Reconnaissance Orbiter. The orbiter passed within 6,000 kilometers of Phobos in March of 2008, which is when this picture was taken. The image is color-enhanced, and the presence of a light blue coloration on the crater's rim could mean that the surface is newly exposed. Streaks on the crater may indicate that, over time, material has slid down the crater walls and into the crater itself. Grooves along the surface are also visible, but their origin is still under question.

APOD 2.1 Blue Sun Bristling

This image of our sun was taken at the Hydrogen-Alpha wavelength of the spectrum. Hydrogen-Alpha's wavelength is 656 nm. The image was then inverted to appear blue. The sun is mostly composed of hot hydrogen gas. Taken at the Hydrogen-Alpha wavelength, the sun's chromosphere is easily visible. Spicules, thin long tubes about the length of the radius of the Earth that are composed of magnetically-confined hot gas, can also be seen bursting from the sun. Many people believe that the sun is on fire, but this is far from the truth. The sun has barely any Oxygen, which is essential to fire. In reality, the sun is just extremely hot gas. Energy from the sun is due to the fusion of hydrogen and helium in the core of the sun. Solar prominences can also be seen extending from the sun. Average size prominences extend many thousands of kilometers into space. However, in the picture they appear very tiny. This evidence shows how massive the sun really is. Sunspots, often visible on the sun, were not visible on the day that this photo was taken.