You are here: Home / Archives for polar
The Sky is Waiting.
Search AstroGuyz
Custom Search
Advertise on Astroguyz!
|
|
|
 |
|
Pictured is a Delta IV rocket launch from Cape Canaveral on November 21st, 2010. The image is a 20 second exposure taken at dusk, shot from about 100 miles west of the launch site. The launch placed a classified payload in orbit for the United States Air Force.
Difficult but not impossible to catch against the dawn or dusk sky, spotting an extreme crescent moon can be a challenge. The slender crescent pictured was shot 30 minutes before sunrise when the Moon was less than 20 hours away from New. A true feat of visual athletics to catch, a good pair of binoculars or a well aimed wide field telescopic view can help with the hunt.
The Sun is our nearest star, and goes through an 11-year cycle of activity. This image was taken via a properly filtered telescope, and shows the Sun as it appeared during its last maximum peak in 2003. This was during solar cycle #23, a period during which the Sun hurled several large flares Earthward. The next solar cycle is due to peak around 2013-14.
Located in the belt of the constellation Orion, Messier 42, also known as the Orion Nebula is one of the finest deep sky objects in the northern hemisphere sky. Just visible as a faint smudge to the naked eye on a clear dark night, the Orion Nebula is a sure star party favorite, as it shows tendrils of gas contrasted with bright stars. M42 is a large stellar nursery, a star forming region about 1,000 light years distant.
Orbiting the planet in Low Earth Orbit (LEO) every 90 minutes, many people fail to realize that you can see the International Space Station (ISS) from most of the planet on a near-weekly basis. In fact, the ISS has been known to make up to four visible passes over the same location in one night. The image pictured is from the Fourth of July, 2011 and is a 20 second exposure of a bright ISS pass.
Next to the Sun, the two brightest objects in the sky are the Moon and the planet Venus. In fact, when Venus is favorably placed next to the Moon, it might just be possible to spot the two in the daytime. Another intriguing effect known as earthshine or ashen light is also seen in the image on the night side of the Moon; this is caused by sunlight reflected back off of the Earth towards our only satellite.
A mosaic of three images taken during the total lunar eclipse of December 21st, 2010. The eclipse occurred the same day as the winter solstice. The curve and size of the Earth’s shadow is apparent in the image.
25.06.10- MRO and the Case of the Martian Spirals.
Scientists may have solved the formation of one of the more curious features on Mars; the formation of its polar ice spirals. First spotted by NASA’s Mariner 9 spacecraft in 1972, these strange swirling patterns etched in the polar ice caps have remained a mystery. For example, the ice formation actually tends to form against and creep into the prevailing winds. Now Jack Holt and Isaac Smith at the University of Texas have used the Mars Reconnaissance Orbiters (MRO) Shallow Subsurface Radar to shed new light on the mystery. MRO’s radar can penetrate layers of ice that have accumulated over the millennia. During the Viking missions, researcher Alan Howard of the University of Virginia first proposed a mechanism for how these spirals could form via wind sweeping downslope and picking up water vapor and ice crystals and subsequently depositing them on the leeward or sun shadowed side on the opposite side of a trough. This process would be self replenishing as the spiral crept forward, much like glacial movement on Earth. This Sun-wind mechanism never gained wide spread acceptance, however, until close scrutiny by the MRO. The Coriolis force generated by the rotation of Mars adds the final touch, creating the final spiral structure. So why don’t we see similar structures in the polar regions of Earth? In the Arctic and Antarctic, more complex forces come into play; here, local topography overpowers the Coriolis force (remember, Mars, while having a day similar in length to the Earth, is much tinier) and shapes the force of the wind. The findings may also explain a prominent feature in the Martian northern polar cap; the Chasma Boreale, a long gash burrowed deep into the ice. It appears as if this canyon is related to a single ice melt event from 5 to 10 million years ago, and prevailing winds have not allowed for deposition of ice ever since. MRO has even discovered a second unknown chasm as well. The history of the formation of the polar caps all tie in to the Martian climate puzzle; a picture of the tiny world’s climate history is rapidly evolving into a unique story, one that parallels our own but diverges from it as well. What new mysteries does the Martian landscape hold?