Mars reaches opposition on January 29th. At that time, Mars will be on the opposite side of the Earth as the Sun (or, alternatively, Earth will be exactly between Sun and Mars). This happens once every 26 months, simply because of the different orbital speeds of the two planets. Earth takes 365.25 days to orbit the Sun; Mars takes 687 days (1.88 Earth years). Mars will also be at its closest approach to Earth: 99.33 million kilometers (61.5 million miles) on the 27th. A natural result of this is that Mars is very bright in our current night time sky, at magnitude -1, brightening to -1.2 at opposition.

NOTE: to prepare you for my comments below, we measure how far apart objects in the sky appear to be from each other by using angular separation, a measurement in degrees. A simple way to visualize this measurement is to make a fist and extend your arm fully out in front of you (don’t hit anybody!). Your fist covers about 10 degrees of angular separation.

Mars, Regulus, M44 Jan. 11

Mars is leaving Leo and moving into Cancer, with the bright star of Leo, Regulus, 14 degrees eastward, and the Beehive Cluster in Cancer, M44, 9 degrees westward. This week (1/11 – 1/17), Mars is due south between 2:00 and 2:30 am, MST, so it’s easy to spot rising in the east after sunset, or high in the southwest before sunrise. As Mars moves along its orbit, it is approaching the Beehive Cluster. By month’s end, Mars will be within 5 degrees of the Beehive.

Mars, Regulus, M44, Jan. 29th

The Beehive Cluster is a bright open cluster (mag. +4) that is visible to the unaided eye under clear, dark skies. The cluster of a couple hundred stars is best seen with binoculars or a telescope under low power. A waxing Moon the last week of the month will wash out the view of the Beehive, and Full Moon on the night of the 29th will only be 5 degrees away.

New Moon is on January 15th, and there is an annular solar eclipse associated with this new moon, though visible only in the eastern hemisphere. The next solar eclipse visible from Utah and the southwestern US will be on May 20th, 2012.

So goes our yearly battle with the Great Mars Hoax that started in 2003. Each year, several emails make their rounds, promising that Mars will amaze and delight, appearing as large as the Full Moon. This often begins in May or June and continues until early September. We’re sorry, we wish we could get them to stop, we really do!

The History

In August 2003, Earth and Mars were closer together than they had been or would be again for thousands of years…and Mars looked really good through a decent sized telescope. You could even see a little surface detail! (light and dark regions). But to the casual observer, it was just a bright red dot in the night sky. Usually, though, Mars is far from spectacular, not exceptionally bright or even interesting in a small amateur telescope– and that’s the case here. Let me explain.

The Science

These hoax emails use many astronomical terms in order to sound credible, but often incorrectly. They talk of azimuth, altitude, opposition etc but ignore Mars’ actual position in our sky, its orbit, or physics in general (Why be bothered by reality?).

When Mars is at opposition, which means that it is opposite the sun in our sky, they say that it will be as large as the full moon.  From now until about 2014, we are about as far away (at opposition) as we can get from Mars, which makes it appear smaller and dimmer in our sky than normal at that time. Mars will still look like a decently bright star, but that’s about it.

In 2003 Mars was in opposition in August.  In 2009, Mars is NOT in opposition at all, but will reach opposition at the end of January 2010. It’s magnitude in August is not -2.9 as claimed, but about +1, which is MUCH dimmer. The reality is that nothing amazing is happening with Mars, except for our  NASA and ESA space missions there.

What would it take for the hoax to be true???

Hypothetically, if it were possible for Mars to be as large as the full moon, either Mars would have to be made bigger ….

Or it would have to move MUCH closer…

A very reputable link with an enormous amount of info on Mars is here.

The Clark Planetarium solar system fact sheet can be downloaded here.