Tag: astronomy

Fermi detects beams of antimatter produced above thunderstorms on Earth

8:45 pm

More from the AAS meeting: The Fermi Gamma-Ray Space Telescope has detected beams of antimatter produced above Earth’s thunderstorms. Key quote:

Scientists think the antimatter particles were formed in a terrestrial gamma-ray flash, a brief burst produced inside thunderstorms and shown to be associated with lightning. It is estimated that about 500 such flashes occur daily worldwide, but most go undetected. . . . The spacecraft was located immediately above a thunderstorm for most of the observed terrestrial gamma-ray flashes. But, in four cases, storms were far from Fermi. In addition, lightning-generated radio signals detected by a global monitoring network indicated the only lightning at the time was hundreds or more miles away. During one flash, which occurred on Dec. 14, 2009, Fermi was located over Egypt. But the active storm was in Zambia, some 4,500 kilometers (2,800 miles) to the south.

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Kepler’s most recent discovery: A rocky Earthlike planet!

12:40 pm

Bumped. Scroll down for updates!

From the abstract of Geoffrey Marcy’s talk today at 6:30 pm (Eastern) at this week’s meeting in Seattle of the American Astronomical Society:

The NASA Kepler Mission has discovered over 700 candidate planets, with most having diameters less than 5 times that of Earth and some as small as that of Earth. One planet has a radius, mass, and density in a new domain having no counterpart in our Solar System, opening a new chapter in planetary science. [emphasis mine]

A press conference is scheduled for 11 am (Eastern). Stay tuned!

Update I. A NASA press release just made public says that Kepler has discovered a rocky planet only 1.4 times the size of the Earth.

Kepler 10b [is] a rocky planet with a mass 4.6 times that of Earth and with an average density of 8.8 grams per cubic centimeter — similar to that of an iron dumbbell.

The press conference is ongoing, but the Kepler results are still to come.

Update II. The star the planet orbits, Kepler 10, is similar to our Sun in mass and size, but older, about 8 billion years old, and is 560 light years away. Kepler 10 is also a relatively bright star in the Kepler field of view, about 11 magnitude.

The planet’s orbit itself is only 8.4 days long. Its density, 8.8 grams per cubic centimeter, is 8.8 times greater than Earth’s. This data, based on all planet models, also suggests that the planet should be a rocky planet like the Earth, though heavier and larger with a surface gravity twice that of Earth.

Since the planet orbits so close to its sun, it is a scorched world, very hot. The scientists expect that it has no atmosphere. It is also probably tidally locked, with one side always facing its Sun.

Update III: Geoffrey Marcy, one of the world’s premier exoplanet scientists, is now commenting on these Kepler results, saying he considers this discovery “among the most profound discoveries in human history.”

Update IV: In answer to a press question, the scientists speculated that the planet might have formed as a gas giant farther from the star, then migrated inward and had its gas atmosphere stripped away. No one knows yet if this is true however.

Studies of further transits might learn more about the planet, such as the temperatures between its two hemispheres. As the planet orbits the star and its illuminated side comes into view, they can see the change in temperature and thus track it. Right now they think the sunlight side could be as hot as 2500 degrees Fahrenheit.

If you want to watch the press conference for yourself, they will be posting the video here.

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Opportunity takes a rest stop at a crater

9:57 pm

In its 14 mile multi-year trek to Endeavour Crater — now about half completed — the Mars rover Opportunity has stopped to take a short rest stop at a small crater.

The crater, dubbed “Santa Maria Crater” by the scientists who operater Opportunity, is about the size of a football field. What makes it especially interesting are the sharp rocks piled up on its rim, as they are probably debris ejected from the crater at impact. Since this material probably came from deep below the Martian surface, it is also likely to hold information about the Martian geological past, thereby making it a prime research site.

Santa Maria crater

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The sun found to vary in unexpected ways

11:06 am

Recent monitoring of the Sun’s brightness as it went from maximum to minimum in its solar cycle has found that, surprisingly, the changes in brightness across different wavelengths do not necessarily vary in lockstep. Key quote:

SIM suggests that ultraviolet irradiance fell far more than expected between 2004 and 2007 — by ten times as much as the total irradiance did — while irradiance in certain visible and infrared wavelengths surprisingly increased, even as solar activity wound down overall. The steep decrease in the ultraviolet, coupled with the increase in the visible and infrared, does even out to about the same total irradiance change as measured by the TIM during that period, according to the SIM measurements.

The stratosphere absorbs most of the shorter wavelengths of ultraviolet light, but some of the longest ultraviolet rays (UV-A), as well as much of the visible and infrared portions of the spectrum, directly heat Earth’s lower atmosphere and can have a significant impact on the climate. [emphasis mine]

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A Martian eclipse

9:39 am

The hubbub about this week’s lunar solstice eclipse was, from my perspective, mostly manufactured press blather. For those who had never seen a lunar eclipse, it was a spectacular experience, but there really was nothing scientifically or technically unique about the fact that it happened to occur on the solstice.

However, below is an eclipse that is definitely unique both technically and scientifically. Scientists using the Mars rover Opportunity have filmed an eclipse on Mars, showing the Martian moon Phobos crossing in front of the Sun. Consider the engineering accomplishment: not only did they need to be able to calculate exactly when this would happen at a very particular spot on the Martian surface, they had to have a camera there able to take the movie. And they had to operate it from Earth!

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Scientist makes the first measurements of the magnetic field at the Earth’s core

5:55 pm

A scientist has made the first measurements of the strength at the Earth’s core of its magnetic field. What’s most fascinating is that he used the Moon and distant quasars to do it! First he used radio observations of the quasars to get very precise measurements of the Earth’s rotation axis and how the Moon was tugging at that axis and thus affecting its magnetic field. Then,

By calculating the effect of the moon on the spinning inner core, Buffett discovered that the precession makes the slightly out-of-round inner core generate shear waves in the liquid outer core. These waves of molten iron and nickel move within a tight cone only 30 to 40 meters thick, interacting with the magnetic field to produce an electric current that heats the liquid. This serves to damp the precession of the rotation axis. The damping causes the precession to lag behind the moon as it orbits the earth. A measurement of the lag allowed Buffett to calculate the magnitude of the damping and thus of the magnetic field inside the outer core.

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Amino acids found on meteorite that crashed in the Sudan

12:09 am

Dead alien life arrives on Earth! Not really but still exciting anyway: Scientists have found the remains of space-born amino acids — essential to life — in the meteorite that crashed in the Sudan in 2008. Key quote:

“This meteorite formed when two asteroids collided,” said Daniel Glavin of NASA’s Goddard Space Flight Center in Greenbelt, Md. “The shock of the collision heated it to more than 2,000 degrees Fahrenheit [1,093 degrees Celsius], hot enough that all complex organic molecules like amino acids should have been destroyed, but we found them anyway.”

The discovery is further evidence that the basic elements of life can form in even the most hostile of environments.

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The last remant of a supernova

9:30 am

Time for some astronomical sightseeing! This image, produced from data taken by both the Hubble Space Telescope and the Chandra X-ray Observatory, shows what astronomers call a supernova remnant. The bubble, located in the Large Magellanic Cloud 160 thousand light years away, is thought to be 23 light years across and expanding about 11 million miles per hour. It is thought that the supernova itself took place around 1600. That we have no record of it is probably because it was only visible in the southern hemisphere, where few records of such events were being kept at that time. More here, including the image using only Hubble data as well as a video animation that is quite stunning.

Supernova remnant

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