Mars: On the Move

Red planet Mars continues to shine brightly all night long, rising in the east before sunset. Late last month, Earth passed Mars in its orbit, and the two planets were just 61 million miles (97.6 million km) apart, closer to each other than they’ll be until 2014. The distance between Earth and Mars is now increasing, and our nearest planetary neighbor in space will dim slightly every night.

Mars is currently in the middle of what astronomers call a retrograde loop. As Mars orbits around the Sun, the planet typically travels from west to east through the constellations as seen from Earth. But as Earth passes by Mars, the red planet appears to travel backwards in the sky, moving east to west. This backwards loop began on December 22, 2009, and will end on March 11, 2010.

As February begins, Mars appears near the center of Cancer the crab. Cancer is a faint constellation, so unless you have a perfectly dark sky, you probably won’t see it. Instead, look between the brighter constellations of Leo the lion and Gemini the twins to determine Cancer’s location in the sky.

On the evening of February 6th, Mars will appear near the open star cluster called the Beehive or M-44. This will make a pretty sight through binoculars or small telescope.

By the end of February, Mars will appear closer to Gemini, but in March, Mars will seem to slow down, stop, and reverse direction, heading back toward Leo! You can even use this star chart to track Mars’ position against the background stars now through April 1st.

Why does Mars perform this backward dance? Mars isn’t really changing its motion. It’s easy to forget that Earth is also in motion!

Imagine yourself in the driver’s seat of a fast-moving racecar on the inside track. Think about what you would see out the window as your car comes from behind and passes a slower moving car on the outside track. The slower car gets closer and closer until you pass it. As you speed past, it looks as though the other car is moving backwards. Similarly, as Earth speeds past Mars, Mars looks like it’s going backwards!

Spirit: Not Quite so Much

Meanwhile on Mars, the rover Spirit is stuck, possibly never to move again. In April 2009, Spirit’s three left wheels broke through a crusty top surface layer, sinking into a strange powdery substance. After months of effort by the rover team, Spirit hasn’t been able to free herself.

In late January 2010, Spirit was declared a “stationary science platform.” But despite early reports and rumors in the media and on Twitter, Spirit is not dead.

During February and March, the rover team will try to position Spirit so her dusty solar panels face the low winter Sun to generate as much power as possible. It will take all her strength to survive the frigid Martian winter where temperatures will drop below -45°F.

If Spirit makes it through the winter, she will resume science operations in August of 2010. Of all the places Spirit could have gotten stuck, this is one of the best. The robotic arm will be able to conduct experiments on everything it can reach. That powdery substance may be evidence of a hydrothermal steam vent from long ago.

Spirit’s stationary status also opens the door to new scientific exploration. By monitoring Spirit’s radio transmissions very closely for six months, researchers can measure the rotation of Mars with great precision. The results may tell us whether Mars has a partially liquid iron core or if the core is completely solid.

On the other side of Mars, Spirit’s twin Opportunity continues to rove. You can follow the day-to-day adventures of both rovers at marsrovers.jpl.nasa.gov. And here on Earth, preparations are underway for a new rover, the Mars Science Laboratory “Curiosity” to launch in 2011.

Join us for Mars Update in the Sudekum Planetarium to learn more about these daring explorers, their monumental discoveries and the latest news. The story isn’t over!

Wintertime Stars

Don’t let cold weather stop you from looking at the night sky. The winter sky features the brightest stars of the year, and the cold crisp air is free of the haze that tends to soften the summer night sky.

So bundle up and step outside. A great place to start is mighty Orion the hunter high in the south in the early evening. His shoulders, belt, and feet form a distinctive pattern that can be seen even with strong light pollution.

Draw an imaginary line from Orion’s bright blue foot Rigel through his red shoulder Betelgeuse and continue that line up towards Gemini the twins. Depending on how dark your local skies are, you might only see the two stars that mark the heads of the twins, Castor and Pollux. Like real twins, these two stars can be hard to tell apart. Remember that Pollux is nearest Procyon in Canis Minor the small dog, and Castor is nearest Capella in Auriga the charioteer.

Upcoming Star Parties

The next two FREE public star parties are Saturday, February 20 from 7:30 to 9:30 pm at Shelby Bottoms Nature Center, and Saturday, March 20 from 8:00 to 10:00 pm at the Special Events Field at Edwin Warner Park. Members of the Barnard-Seyfert Astronomical Society will set up telescopes to provide close up views of the late winter night sky. Odds are it will be cold, so dress warmly!

If the weather is cloudy or worse, the star party will be cancelled. If the weather is questionable, check our home page or call AstroLine at 615-401-5092 before traveling.