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.

• Space.com on 2009 BD.
• Space.com on a previous corkscrewing asteroid.
• Spaceweather.com notes the flyby.

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.

• Universe Today on the approach of Comet Lulin.
• Visual Astronomy discusses Comet Lulin.
• Sky and Telescope gives viewing information.

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.

• Science Centric on the supernova remnant.
• Students for the Exploration and Development of Space on Tycho's supernova.

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.

• National Radio Astronomy Observatory news release on the discovery.

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.

• Hubble Finds Stars That Go "Ballistic"
• Brown Dwarfs Don't Hang Out With Stars
• Star Light, Star Bright, Its Explanation is Out of Sight

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.

• NASA's Mars Rover Web site.

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.

• Solar Views information on Venus.
• Sky & Telescope This Week's Sky at a Glance.
• Planet Venus on observing Venus.

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.

• Science Daily on the solar wind question.
• Science@NASA on the solar wind and magnetic fields of Mars.