No, Mars Won’t Look as Big as the Moon in August

Have you gotten a copy of the email yet? If you haven’t, you probably will. Forwarded from a friend, forwarded again and again until the original source is lost in the murky cloud of the Internet, it encourages you to get set for the experience of a lifetime. When MARS WILL LOOK AS LARGE AS THE FULL MOON!!!!! Is this going to happen? No. But there’s a strange gem of truth at the heart of this misunderstanding/hoax. I’ll give you the history and then everything you need to explain what’s going on to your excited but misinformed email forwarding friends.

Turn back the clock to August 2003 for Mars Mania. Astronomers were reporting that Mars would make its closest approach to the Earth in more than 60,000 years. On August 27th, 2003, Mars closed the distance to only 55,758,006 kilometers (34,646,418 miles). Since Mars and the Earth both orbit the Sun, the distance between them grows and shrinks. The most distant they get is 400 million km (250 million miles).

If those sound like meaningless numbers, lets put them in context. The Moon orbits the Earth at about 385,000 km (240,000 miles). Mars can range between 144 and 1041 times as far away as the Moon. In other words, even at this closest point back in August 2003, Mars was relatively close for Earth-Mars standards, but still 144 times further away than the Moon.

August 2003 was a wonderful time to look through a telescope at Mars. It looked huge, bright, and features on the surface were easy to see. But times like this actually happen roughly every 2 years, when Earth catches up to Mars as they orbit the Sun. This close approach happened again on October 29, 2005, and it’s going to happen on December 18, 2007.

Back to that email.

Here’s what it says:

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 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.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