It's Mars Hoax Season

Well, it's that time of year again. I got my first email of the Mars Hoax Season. The Mars Hoax Season reaches its height in August when emails are flying around the internet claiming Mars will be as big as the full Moon. Here is the one I got this morning.

The Red Planet is about to be spectacular! This month and next, Earth is catching up with Mars in an encounter that will culminate in the closest approach between the two planets in recorded history. The next time Mars may come this close is in 2287. Due to the way Jupiter's gravity tugs on Mars and perturbs its orbit, astronomers can only be certain that Mars has not come this close to Earth in the Last 5,000 years, but it may be as long as 60,000 years before it happens again.

The encounter will culminate on August 27th when Mars comes to within 34,649,589 miles (55,763,108 km) of Earth and will be (next to the moon) the brightest object in the night sky. It will attain a magnitude of -2.9 and will appear 25.11 arc seconds wide. At a modest 75-power magnification Mars will look as large as the full moon to the naked eye. Mars will be easy to spot. At the beginning of August it will rise in the east at 10 p.m. and reach its azimuth at about 3 a.m.

By the end of August when the two planets are closest, Mars will rise at nightfall and reach its highest point in the sky at 12:30 a.m. That's pretty convenient to see something that no human being has seen in recorded history. So, mark your calendar at the beginning of August to see Mars grow progressively brighter and brighter throughout the month. Share this with your children and grandchildren. NO ONE ALIVE TODAY WILL EVER SEE THIS AGAIN

Well, there is almost always a kernal of truth in these things. This hoax originated in 2003 when Mars really did come within 35 million miles of Earth. That really was an unusually close approach and Mars appeared much brighter than usual. The problem is that the original article had a line about when viewed through a telescope at 75x (75 times actual size) Mars would appear the same size as the full Moon. In other words, Mars without a telescope, Mars would be 1/75 as large as the full Moon (not nearly as impressive).

Mars has a very elliptical orbit so sometimes we have closer approaches than others. The most recent opposition (i.e. closest approach) occurred on January 29th, 2o10 and Mars was about 99 million kilometers (about 60 million miles) away.

Now something cool is happening with Mars right now. Mars, Saturn, Venus and (for sharp eyed observers) Mercury are putting on a show in the west after sunset the next few weeks. I took this picture last night and have labeled the visible planets.

I was out a little later and Mercury already set (and is tough to see during this opposition). You might notice that Mars does not exactly look as big as the full Moon. To top if off, Mars is moving farther away from Earth!

During the next couple of weeks, Saturn and Mars will move closer to Venus. Mercury will hang out beneath them, but Mercury will never get very high in the sky and will be difficult to see. Mars, Venus and Saturn will make a lovely trio in their own right and you should get out there and take a look. Here is a snapshot of what you have to look forward to on August 9th (at 8pm from Tucson, your results may vary).

The crescent Moon will join the party on August 12th and 13th (just in time for the Perseid meteor shower...more on that later!) You can bet I will be out fighting the Arizona monsoons trying to find breaks in the clouds to take pictures of this conjunction!

Reprinted with permission from the Half-Astrophysicist Blog.