The three stars of Orion's Belt.

There are many stars in this image shining through the atmosphere. Why aren't more of them streaked? The answer is : Earth has an exponential atmosphere its density increases very rapidly as you sink into it. Orion's belt stars are the lowest of the bright stars in today's image, hence they are refracted most. A few other stars are at about the same low altitude, but they are too dim to display the faint tails.

They look like meteors flying in formation three stars with upward-pointing tails shining through Earth's airglow layer.What are they?

They are The three stars of Orion's Belt.

NASA scientist Rob Suggs explains: "Orion was setting behind Earth's limb when Don took this picture. His camera was locked on Orion, so Earth's atmosphere moved upward during the exposure. As the Belt stars were covered, they were also deflected upward by atmospheric refraction -- hence the illusion of three meteors in this long exposure. We know that the descent of the setting Sun can be slowed by refraction; this is the same effect."

"The atmosphere acts like a giant lens," agrees expert Les Cowley. "Here on Earth, when we see the setting Sun with its center on the horizon, the uppermost limb of the Sun has, in fact, already set. In such cases, refraction has lifted the upper part of the Sun by 0.25º -- half its apparent diameter. From orbit, light rays enter the Earth's atmosphere and then have an equally tortuous journey out again. Refraction is almost doubled. The setting Sun and setting stars are lifted twice as much."

In a Picture of the Day last week we saw the same thing: Orion's foot, the bright star Rigel, posing as a meteor as it set behind Earth's limb. "A magnified image of Rigel reveals a streak dimming and reddening in the upward direction," notes Cowley. "The reddening is caused by the atmosphere scattering more blue light than it does red."

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The Sun Sets Twice

Where the Sun Sets Twice

NASA's Kepler mission has discovered a world where two suns set over the horizon instead of just one. The planet, called Kepler-16b, is the most "Tatooine-like" planet yet found in our galaxy and is depicted here in this artist's concept with its two stars. Tatooine is the name of Luke Skywalker's home world in the science fiction movie Star Wars. In this case, the planet it not thought to be habitable. It is a cold world, with a gaseous surface, but like Tatooine, it circles two stars. The largest of the two stars, a K dwarf, is about 69 percent the mass of our sun, and the smallest, a red dwarf, is about 20 percent the sun's mass.

Most of what we know about the size of stars comes from pairs of stars that are oriented toward Earth in such a way that they are seen to eclipse each other. These star pairs are called eclipsing binaries. In addition, virtually all that we know about the size of planets around other stars comes from their transits across their stars. The Kepler-16 system combines the best of both worlds with planetary transits across an eclipsing binary system. This makes Kepler-16b one of the best-measured planets outside our solar system.

Kepler-16 orbits a slowly rotating K-dwarf that is, nevertheless, very active with numerous star spots. Its other parent star is a small red dwarf. The planetary orbital plane is aligned within half a degree of the stellar binary orbital plane. All these features combine to make Kepler-16 of major interest to studies of planet formation as well as astrophysics.

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A Star Formations

The dwarf galaxy NGC 4214 is ablaze with young stars and gas clouds. Located around 10 million light-years away in the constellation of Canes Venatici (The Hunting Dogs), the galaxy's close proximity, combined with the wide variety of evolutionary stages among the stars, make it an ideal laboratory to research the triggers of star formation and evolution. .

Cepheus B, a molecular cloud located in our Milky Galaxy about 2,400 light years from the Earth, provides an excellent model to determine how stars are formed. This composite image of Cepheus B combines data from the Chandra X-ray Observatory and the Spitzer Space Telescope.

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The Brightness of the Sun

The bright sun, a portion of the International Space Station and Earth's horizon are featured in this image photographed during the STS-134 mission's fourth spacewalk in May 2011. The image was taken using a fish-eye lens attached to an electronic still camera.

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New Planet Discovered

Image above: These time-lapse images of a newfound planet in our solar system, called 2003UB313, were taken on Oct. 21, 2003, using the Samuel Oschin Telescope at the Palomar Observatory near San Diego, Calif. The planet, circled in white, is seen moving across a field of stars. The three images were taken about 90 minutes apart.


Scientists did not discover that the object in these pictures was a planet until Jan. 8, 2005. Image credit: Samuel Oschin Telescope, Palomar Observatory

Image above: This artist's concept shows the planet catalogued as 2003UB313 at the lonely outer fringes of our solar system. Our Sun can be seen in the distance. The new planet, which is yet to be formally named, is at least as big as Pluto and about three times farther away from the Sun than Pluto. It is very cold and dark.

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The Legend Of Crop Circle

A crop circle is a sizable pattern created by the flattening of a crop such as wheat, barley, rye, maize, or rapeseed. Crop circles are also referred to as crop formations, because they are not always circular in shape. While the exact date crop circles began to appear is unknown, the documented cases have substantially increased from the 1970s to current times. Twenty-six countries ended up reporting approximately ten-thousand crop circles, in the last third of the 20th century, and 90% of those were located in southern England. Many of the formations appearing in that area are positioned near ancient monuments, such as Stonehenge. Formations usually are made overnight, but have also been made during the day. The most widely known method for a person or group to construct a crop formation is to tie one end of a rope to an anchor point, and the other end to a board which is used to crush the plants. More recent methods include the use of a lawn roller.

Some crop formations are paid for by companies who use them as advertising. Other formations are sometimes claimed by individuals or groups without any evidence to support their assertion, usually after undesirable legal repercussions become unlikely.

History of Crop Circle

Certain evidence, such as the Mowing-Devil, suggest the appearance of crop circles well before the 20th century. Nevertheless, there are important differences between that story and modern crop circles. The story of the mowing devil involves the cutting of the crops following a dispute over crop harvesting and an invocation of the devil, no geometric patterns were reported.

Certain evidence, such as the Mowing-Devil, suggest the appearance of crop circles well before the 20th century. Nevertheless, there are important differences between that story and modern crop circles. The story of the mowing devil involves the cutting of the crops following a dispute over

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A Planet as Big as Its Star

This artist's concept shows the smallest star known to host a planet. The planet, called VB 10b, was discovered using astrometry, a method in which the wobble induced by a planet on its star is measured precisely on the sky.

The dim, red star, called VB 10, is a so-called M-dwarf, located 20 light-years away in the constellation Aquila. It has only one-twelfth the mass, and one-tenth the size, of our sun. The planet is a gas giant similar in size to Jupiter but with six times the mass. Though the planet is less massive than its star, the two orbs would have a similar diameter.

VB 10b orbits its star about every 9 months at a distance of 50 million kilometers (30 million miles).

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our planet

The earth has a solid inner core that is surrounded by a liquid outer core. Surrounding the entire dense, metallic core is a thick, hot, convective layer called the mantle. The crust consists of many continental and oceanic plates that have slowly moved and changed positions on the globe throughout geologic time. The movement of these large plates (plate tectonics) has caused the earth’s exposed land surface to change position and shape. Tremendous forces, such as convection, tension and compression, have caused the upper crustal layers to fold and fault. Earthquakes and volcano activity have resulted along the borders of the plates. These forces, along with weathering and erosion, have caused large quantities of material to be deposited in varying amounts across the globe.

            Physical and chemical processes have constantly acted on earth material to form, change and reform three general types of rocks. These processes form minerals, which are substances that consist of certain elements to form compounds that appear to be uniform throughout. Other minerals are pure substances and are made of a single element. Each mineral has unique physical and chemical properties that allow it to be of economic value to humans. Minerals can combine to form rocks. Heat, pressure, erosion, and chemical processes can change rock from one type to another. Earth material can eventually be in the form of any of the rock types found throughout geologic history. This process is known as the rock cycle. 

            The upper-most layer of the continental crust is covered by soil. The ingredients in soils can vary from neighborhood to neighborhood and around the earth. Different soils have different properties and compositions of sand, silt, clay and humus. Soils have many properties such as texture, particle size, pH, fertility and ability to hold moisture. Depending upon the combination of properties, soils have a great variability in their ability to support structures and plant growth. Humans have continually decreased the amount of soil that is available through poor land-use methods, soil nutrients depletion, and the construction of structures that cover the soil (such as highways, parking lots and buildings). Structures that cover the soil also affect a run-off pattern, which leads to another set of problems.

            Technology such a remote sensing has allowed humans to better study the human impact on soil quality and erosional processes so that soil can be protected and preserved. Over time, remote sensing information can tell us how humans are constantly changing the surface of the earth. Technologies can also assist in finding ways to help prevent erosion. It is important that humans be stewards of the pedosphere.

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