SkyCaramba weekly astronomy blog for the week ending September 10, 2011
Now’s a good time to start watching Mars. The Red Planet is a morning object in Gemini now. If you look at it in a telescope, you’ll see Mars in an almost perpendicular view. The planet goes through its northward equinox on September 13th.
That’s the equinox like the one we have in March on Earth. The sun will directly over the Martian equator on that day. And everywhere on Mars, there will be 12 hours, 20 minutes of daylight followed by the same length of nighttime. One complete day on Mars is 24 hours, 40 minutes as we measure it on Earth.
Keep watching Mars over the next few months and you’ll see it get bigger in your telescope and you’ll see its north pole coming into view. It’s getting bigger because Earth is getting closer. Its north pole is coming into view because, like Earth, Mars rotates on a tilted axis. The tilted axis is why we have seasons.
You’ll find Mars in Gemini now. It’s moving quickly through the morning sky toward Cancer. It’ll be in the heart of Cancer as October starts. The view through binoculars or a telescope will be a good one with the Red Planet in a star cluster called the Beehive. Most of the stars in the Beehive are at least 500 light years away.
After the Beehive, Mars speeds over to Leo. It will rendezvous with the bright star Regulus in November. The moon will pass by them both the 18th of that month. In January, Mars seems well on its way out of Leo when it slows down, turns around, and heads back. It makes it almost all the way back to Regulus in April. But it turns around again before it gets there.
Mars is rising earlier each morning. It’ll become a late evening object before the year ends and it’ll be up all night in February.
Probably in the next few months you’ll get an email telling you Mars will look as big as the full moon. That’s not true. Mars will be at opposition on February 3, 2012. That’s when Earth is closest to Mars and Mars is on the opposite side of the sky as the sun. It will look bigger in a telescope because it’ll be closer than it’s been in about two years. But it won’t look as big as the full moon. It never gets that close. The misinforming email has been going around every time Mars has approached opposition since 2003.
The 2003 opposition was spectacular. Mars was just 34 million miles (about 54 million kilometers) from Earth. The two planets hadn’t been so close in almost 60,000 years! The 2012 event won’t be so close. The Red Planet will be 71 million miles (about 114 million kilometers) away. But it’s still the best view you’ll get in a telescope for two years. I say two years, because it takes Mars that long to be at opposition again.