Show 206: Corkscrewing Asteroids

February 19, 2009

The typical, corkscrewing path of a
The typical, corkscrewing path of a "co-orbital" asteroid. Credit: Paul Weigert

Asteroids that drift around the solar system at nearly the same distance from the Sun as the Earth’s orbit, can “corkscrew” into Earth’s vicinity as they pass by. These are not common but they do occur. The most recent one, 2009 BD, passed within 400,000 miles of Earth. It is corkscrewing near Earth, and then in the future may drift away.

A similar object, called 2003 YN107, came by in 2003 and departed the vicinity of the Earth in 2008. It might return in 60 years.

Show 205: New Comet Spied

February 12, 2009

Comet Lulin. Credit: Lulin Observatory
Comet Lulin. Credit: Lulin Observatory

A new comet will likely become visible in dark skies in late February. Comet Lulin was discovered in July 2007 and should be just on the edge of naked-eye visibility in dark, moonless skies. It should be easily seen in binoculars, but note that comet brightness estimates are notoriously unreliable since comets can change their appearance dramatically and quickly.

Show 204: Ancient Supernova Mystery Solved

February 5, 2009

A composite image of Tycho’s supernova remnant in infrared and X-rays.
A composite image of Tycho’s supernova remnant in infrared and X-rays.

In 1572, a “new star” appeared in the sky, stunning astronomers and challenging ancient theories of the universe. The brilliant supernova, recorded by the astronomer Tycho Brahe, was even visible during the day. Now astronomers have been able to capture faint “light echoes” of original explosion, helping to determine the exact type of supernova Tycho saw. It was likely caused by a white dwarf star undergoing titanic, thermonuclear explosion.

Show 203: A More Massive Milky Way

January 29, 2009

A composite color infrared image of the center of our Milky Way galaxy. Credit: NASA, JPL, ESA, and Q.D. Wang (University of Massachusetts, Amherst) and S. Stolovy (Spitzer Science Center/Caltech)
A composite color infrared image of the center of our Milky Way galaxy. Credit: NASA, JPL, ESA, and Q.D. Wang (University of Massachusetts, Amherst) and S. Stolovy (Spitzer Science Center/Caltech)

Our Milky Way galaxy is known to be massive, but new observations of the speed of star formation along its spiral arms indicate it is much more massive than previously thought. The observations of radio emissions from star formation regions were taken with the Very Long Baseline Array (VLBA), a suite of radio telescope scattered across the globe that work together to map details of regions in the galaxy.

Show 202: HubbleWatch for January 2009

January 29, 2009

Hyperactive stars are found racing through the galaxy, creating glowing arrowhead-shaped structures in the drifting gas of the universe. Brown dwarfs, odd objects that are neither stars nor planets, prefer an exclusive club. And scientists are stumped by a flash in the sky that matches nothing on record.

Show 201: Mars Rovers Celebrate Anniversary

January 22, 2009

A false-color image taken by Opportunity shows the rover's tracks.
A false-color image taken by Opportunity shows the rover's tracks.

Those amazing Mars rovers are still at it after their 5th birthday. Although it was a dark and dusty winter for Spirit, the rover appears to still be alive and may have a new destination, since more sunlight is available to power the rover during Martian spring and summer. Opportunity is already off to its new adventure at Victoria Crater, six miles (10 km) away.

Show 200: Views of Venus

January 15, 2009

The Magellan spacecraft took this image of Venus.
The Magellan spacecraft took this image of Venus.

Venus has graced the evening sky for months now, and in the next few weeks it approaches its highest (Jan. 14) and brightest (Feb. 20) in evening sky. Venus is always brighter than the brightest stars — bright enough to be seen even in the middle of the day, if you know where to look. On dark nights, it can be bright enough to cause shadows. Look toward the southwest sky after sunset, and Venus appears above where the Sun has set. It will look like a brilliant white star.

Show 199: Solar Wind Rips Up Mars Atmosphere

January 8, 2009

The Sun sets on Mars in this image taken by the Spirit rover.
The Sun sets on Mars in this image taken by the Spirit rover.

Mars has an extremely thin atmosphere compared to Earth’s. But scientists think the red planet once had a thick atmosphere of carbon dioxide. Where did it go? Scientists now think it’s possible that Mars’ uneven magnetic field may have contributed to the stripping away of the atmosphere by the solar wind.