Called the eXtreme Deep Field, or XDF, the photo was assembled by combining 10 years of Hubble photographs taken of a patch of sky. The XDF is a small fraction of the angular diameter of the full moon…and contains about 5,500 galaxies. The faintest galaxies are one ten-billionth the brightness of what the human eye can see.
The moon orbits around the earth every 29.5 days and since our months typically have 30-31 days that leaves some leftover time (0.5-1.5 days). Eventually that adds up and we get an extra cycle in one month, and that means an extra full moon. Typically, months only get one full moon and so having two is pretty rare, happening every 2.7 years.
Hence, the phrase, “once in a blue moon,” which is a lot like saying “once in about 3 years”.
I love this stuff (orbits, planets, stars) and have been a star-gazer since I was a kid. If you are too, then you can enjoy the “blue moon” this Friday, August 31, 2012.
Yep, it’s been around three years since the last one (2.67 years to be exact, the last blue moon was on New Year’s Eve – Dec 31, 2009). I also think you should try, at whatever the cost, to say “once in a blue moon” about something. Think of something you know you won’t do or won’t happen until July 2015 (the next blue moon).
A team of astronomers using NASA’s Hubble Space Telescope is reporting the discovery of another moon orbiting the icy dwarf planet Pluto.
The moon is estimated to be irregular in shape and 6 to 15 miles across. It is in a 58,000-mile-diameter circular orbit around Pluto that is assumed to be co-planar with the other satellites in the system.
“The moons form a series of neatly nested orbits, a bit like Russian dolls,” said team lead Mark Showalter of the SETI Institute in Mountain View, Calif.
The discovery increases the number of known moons orbiting Pluto to five.
The Pluto team is intrigued that such a small planet can have such a complex collection of satellites. The new discovery provides additional clues for unraveling how the Pluto system formed and evolved. The favored theory is that all the moons are relics of a collision between Pluto and another large Kuiper belt object billions of years ago.
The new detection will help scientists navigate NASA’s New Horizons spacecraft through the Pluto system in 2015, when it makes an historic and long-awaited high-speed flyby of the distant world.
Infrared imaging by JPL’s Cassini spacecraft has shown the existence of large methane lakes near the equator of Saturn’s moon Titan. One of them is about the size of Utah’s Great Salt Lake at its lowest recorded level and is at least three feet deep. The spacecraft also discovered smaller, shallower “ponds” nearby similar to marshes on Earth, with knee- to ankle-level depths.
Astronomers have previously observed large methane lakes near Titan’s poles, but the discovery of the “tropical” lakes is a surprise because it was generally assumed that this region was too warm to allow such lakes to exist for any length of time. Titan’s weather system is similar to Earth’s in one respect, but with liquid methane instead of water. The methane near the equator evaporates and is transported by winds to the poles, where it condenses back into a liquid.
…Like water vapor, which dissociates in the upper atmosphere to form ozone, methane is also dissociated by sunlight to produce reactive carbon atoms that can combine to form organic chemicals such as amino acids. Such compounds have been detected in Titan’s atmosphere and are the basis of some researchers’ speculation that Titan may harbor life forms of some sort.
In December of 1972, Apollo 17 astronauts Eugene Cernan and Harrison Schmitt spent about 75 hours on the Moon in the Taurus-Littrow valley, while colleague Ronald Evans orbited overhead.
The image shows Schmitt on the left with the lunar rover at the edge of Shorty Crater, near the spot where geologist Schmitt discovered orange lunar soil. The Apollo 17 crew returned with 110 kilograms of rock and soil samples, more than was returned from any of the other lunar landing sites. Now forty years later, Cernan and Schmitt are still the last to walk on the Moon.
For several years scientists have been begging to test their theories about Mercury, the closest planet to the Sun. You see, the radar signals come back showing ice exists on the planet, but how could ice exist on a planet so incredibly hot?
NASA sent the spacecraft MESSENGER to orbit the planet and figure the mystery out (among other things). It turns out that ice exists at the planet north and south poles and possibly underneath some “dirt-shielding”.
All of this was uncovered by Professor David Paige, who has previous experience with Mars and the Moon, as he explains in his own words:
“I was able to use the Mercury laser altimeter in conjunction with a three-dimensional ray-tracing thermal model that I built to study ice on the moon, Paige said. “Using these models, I calculated the average temperature on the surface of the planet and concluded that the surface temperatures were too warm to permit the long-term stability of ice. The only possibility was some sort of thin layer of cover that allowed the ice to survive.”
This thin, dark layer is called a regolith and is probably made of organic substances like the Earth’s soil, rich in hydrocarbon compounds that may have come from the comets and meteorites that struck the planet over time. The comets and meteorites may have also contributed the water that seeped under the soil cover to form the icy patches.
MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging) is the first spacecraft to orbit Mercury. Its goal is to collect better data about the composition and atmosphere of the planet, and it just completed its first year of information gathering.
While the mix of water and organic compounds on another planet may raise the possibility of extraterrestrial life for some scientists, this is not what excites Paige. For him, the discovery of ice on Mercury is the triumph of science.
“We’re getting a good agreement between models and observations,” Paige said. “What we thought was true is true. The most exciting part of this? We may not know lot of things, but on Mercury we have things under control.”
There will be a stunning partial solar eclipse on Sunday, May 20th. The moon will begin shrouding the sun at 5:27 p.m. (PST) and will cover 83 percent of the sun’s surface at 6:40 p.m. The eclipse will take place while the sun is sinking toward the horizon, out over the ocean. It’ll be easy to see, if skies are clear.
Do not — repeat, do not — look at the eclipse with your naked eye or with materials that don’t protect your vision from UV and infrared radiation. You risk permanent and serious damage to your vision if you don’t use the proper safety equipment to view a solar eclipse, and the damage can occur within seconds.