03 - Mercury
at greatest elongation, 27° west
from Sun (morning sky) at 11h UT.
0000Mag.
+0.1. Very low in the east-southeast about 30
minutes before sunrise.
05 - Moon
very near Mercury at 15h UT (morning
sky).
15 - Moon
very near Venus at 20h UT (morning
sky). Daytime occultation visible
0000from
North America and Cuba.
15 - Moon near Mars at 3h UT
(evening sky). Mag. +0.5.
19 - Moon near Saturn at 13h
UT (evening sky). Mag. +0.3.
21 - Spring or vernal equinox
at 5:48 UT. The time when the Sun reaches the
point
0000along the ecliptic
where it crosses into the northern celestial
hemisphere marking
0000the start of
spring in the Northern Hemisphere and autumn
in the Southern
0000Hemisphere.
24 - Mercury 0.97° from Venus at
14h UT (20° from Sun, morning sky).
0000Mags. -0.3
and -3.9. Favors S. Hemisphere skywatchers.
30 - Moon near Jupiter at 19h
UT (morning sky).
00 0 0
0 0 0//
Get the complete calendar version
at skymaps.com
7 -
The
Outrageous Tales of a Space Shuttle Astronaut
- On February 1, 1978, the first group of space shuttle
astronauts, twenty-nine men and six women, were introduced
to the world. Among them would be history makers, including
the first American woman and the first African American
in space. This assembly of astronauts would carry NASA
through the most tumultuous years of the space shuttle
program. Four would die on Challenger. Mullane vividly
portrays every aspect of the astronaut experience --
from telling a female technician which urine-collection
condom size is a fit; to walking along a Florida beach
in a last, tearful goodbye with a spouse; to a wild,
intoxicating, terrifying ride into space; to hearing
"Taps" played over a friend's grave. Mullane is brutally
honest in his criticism of a NASA leadership whose bungling
would precipitate the Challenger disaster.
Thursday, January 17, 2008
Amazing Image of Mercury
Scientists are sifting through their first new views of the planet Mercury in more than three decades thanks to images beamed home by NASA's MESSENGER probe.
The car-sized spacecraft zipped past Mercury in a Monday flyby and is relaying more than 1,200 new images and other data back to eager scientists on Earth.
In one new image, released today, the planet's stark surface is shown peppered with small craters, each less than a mile (1.6 km) in diameter and carved into an area about 300 miles (482 km) across. MESSENGER used its narrow-angle camera to photograph the scene, which is dominated by a large, double-ringed crater dubbed Vivaldi after the Italian composer. While the crater was last seen by NASA's Mariner 10 probe, MESSENGER's camera observed it with unprecedented detail, researchers said. Another new view reveals the first look at the half of Mercury left uncharted by Mariner 10.
During Monday's flyby, MESSENGER skimmed just 124 miles (200 km) above Mercury's surface and snapped photographs of about half of the estimated 55 percent of the planet that remained uncharted after Mariner 10's mission. In addition to imagery, the probe is expected to return a wealth of new observations made by its seven instruments to scrutinize Mercury's surface composition, magnetic field, tenuous atmosphere, unusually high density and other features.
Astronomers from Texas universities found a pair of Jupiter-sized planets around a distant star. The star, HD 155358, that host the planets composed of very poor metals (only about 20 percent as much as the Sun). The fact that the star is lacking in metals has challanged the theories of planet formation. HD 155358 is slightly hotter than the Sun, but a bit less massive. Along with one other star (called HD 47536), HD 155358 contains the fewest metals of any star found to harbor planets.
One planet of the HD 155358 has an orbital period of 195 days and, at a minimum, is 90 percent as massive as Jupiter. It orbits HD 155358 at a distance of 0.6 AU. (An astronomical unit, or AU, is the Earth-Sun distance of 150 million km, or 93 million miles.) The other planet orbits HD 155358 in 530 days, with a minimum mass half that of Jupiter, at a distance of 1.2 AU.
NASA Telescope Finds Planets Thrive Around Stellar Twins
The double sunset that Luke Skywalker gazed upon in the film "Star Wars" might not be a fantasy. Astronomers using NASA's Spitzer Space Telescope have observed that planetary systems – dusty disks of asteroids, comets and possibly planets – are at least as abundant in twin-star systems as they are in those, like our own, with only one star. Since more than half of all stars are twins, or binaries, the finding suggests the universe is packed with planets that have two suns. Sunsets on some of those worlds would resemble the ones on Luke Skywalker's planet, Tatooine, where two fiery balls dip below the horizon one by one.
Previously, astronomers knew that planets could form in exceptionally wide binary systems, in which stars are 1,000 times farther apart than the distance between Earth and the sun, or 1,000 astronomical units. Of the approximately 200 planets discovered so far outside our solar system, about 50 orbit one member of a wide stellar duo.
The new Spitzer study focuses on binary stars that are a bit more snug, with separation distances between zero and 500 astronomical units. Until now, not much was known about whether the close proximity of stars like these might affect the growth of planets. Standard planet-hunting techniques generally don't work well with these stars, but, in 2005, a NASA-funded astronomer found evidence for a planet candidate in one such multiple-star system (http://www.jpl.nasa.gov/news/news.cfm?release=2005-115).
Trilling and his colleagues used Spitzer's infrared, heat-seeking eyes to look not for planets, but for dusty disks in double-star systems. These so-called debris disks are made up of asteroid-like bits of leftover rock that never made it into rocky planets. Their presence indicates that the process of building planets has occurred around a star, or stars, possibly resulting in intact, mature planets.
In the most comprehensive survey of its kind, the team looked for disks in 69 binary systems between about 50 and 200 light-years away from Earth. All of the stars are somewhat younger and more massive than our middle-aged sun. The data show that about 40 percent of the systems had disks, which is a bit higher than the frequency for a comparable sample of single stars. This means that planetary systems are at least as common around binary stars as they are around single stars.
In addition, the astronomers were shocked to find that disks were even more frequent (about 60 percent) around the tightest binaries in the study. These coziest of stellar companions are between zero and three astronomical units apart. Spitzer detected disks orbiting both members of the star pairs, rather than just one. Extra-tight star systems like these are where planets, if they are present, would experience Tatooine-like sunsets.
Spitzer Captures Feeble Lights from Distant Worlds
NASA's Spitzer Space Telescope has captured for the first time enough light from planets outside our solar system, known as exoplanets, to identify signatures of molecules in their atmospheres. The landmark achievement is a significant step toward being able to detect possible life on rocky exoplanets and comes years before astronomers had anticipated.
Spitzer, a space-based infrared telescope, obtained the detailed data, called spectra, for two different gas exoplanets. Called HD 209458b and HD 189733b, these so-called "hot Jupiters" are, like Jupiter, made of gas, but orbit much closer to their suns.
The data indicate the two planets are drier and cloudier than predicted. Theorists thought hot Jupiters would have lots of water in their atmospheres, but surprisingly none was found around HD 209458b and HD 189733b. According to astronomers, the water might be present but buried under a thick blanket of high, waterless clouds.
Those clouds might be filled with dust. One of the planets, HD 209458b, showed hints of tiny sand grains, called silicates, in its atmosphere. This could mean the planet's skies are filled with high, dusty clouds unlike anything seen around planets in our own solar system. Source:NASA's Spitzer News Release
A new image from NASA's Hubble Space Telescope shows the colorful "last hurrah" of a star like our sun. The picture was taken on Feb. 6, 2007 , by Hubble's Wide Field and Planetary Camera 2, which was designed and built by NASA's Jet Propulsion Laboratory, Pasadena , Calif.
The star is ending its life by casting off its outer layers of gas, which formed a cocoon around the star's remaining core. Ultraviolet light from the dying star makes the material glow. The burned-out star, called a white dwarf, is the white dot in the center. Our sun will eventually burn out and shroud itself with stellar debris, but not for another 5 billion years.
Our Milky Way galaxy is littered with these stellar relics, called planetary nebulae. The objects have nothing to do with planets. Eighteenth- and nineteenth-century astronomers named them that because through small telescopes they resembled the disks of the distant planets Uranus and Neptune. The planetary nebula in this image is called NGC 2440. The white dwarf at the center of NGC 2440 is one of the hottest known, with a surface temperature of nearly 200,000 degrees Celsius (400,000 degrees Fahrenheit). The nebula's chaotic structure suggests that the star shed its mass episodically. During each outburst, the star expelled material in a different direction. This can be seen in the two bow tie-shaped lobes. The nebula also is rich in clouds of dust, some of which form long, dark streaks pointing away from the star. NGC 2440 lies about 4,000 light-years from Earth in the direction of the constellation Puppis. The colors in the image correspond to material expelled by the star. Blue corresponds to helium; blue-green to oxygen, and red to nitrogen and hydrogen.
The
Oort cloud, is a postulated spherical cloud
of comets situated about 50,000 to 100,000 AU from
the Sun. This is approximately 1000 times the distance
from the Sun to Pluto or roughly one light year, almost
a quarter of the distance from the Sun to Proxima
Centauri, the star nearest the Sun. The Oort cloud
would have its inner disk at the ecliptic from the
Kuiper belt. Although no direct observations have
been made of such a cloud, it is believed to be the
source of most or all comets entering the inner solar
system (some short-period comets may come from the
Kuiper belt), based on observations of the orbits
of comets. Source: Wikipedia
Spitzer Captures Feeble Lights from Distant Worlds 
