Astro Bob blog: Red Planet ruse on the loose againIf you've heard Mars is going to be an incredible sight next month, please read this
By: Bob King, Duluth News Tribune
Red Planet ruse on the loose again
A few readers have written to ask about an e-mail they've received about the planet Mars being closer to Earth next month than at any time in history. Here's a typical read gathered from snopes.com:
++The Planet Mars will be brightest in the night sky starting in August. It will look as large as the full moon to the naked eye. Be sure to watch the sky on August 27 at 12:30 a.m. It will look like the Earth has two moons. NO ONE ALIVE TODAY WILL EVER SEE IT AGAIN++
Look familiar? Too bad it's not true. I should say it was true once, sort of. Back in 2003, Mars really was near the Earth, something that happens every 15-17 years. That particular approach was a record breaker because it was the closest in nearly 60,000 years. Mind you, other close approaches are only slightly more distant. You and I wouldn't notice the difference either with our eyes or through a telescope.
The message goes to compare the Red Planet's size to the full moon. This unfortunate error is also based on a shard of truth. Through a telescope with modest magnification, Mars did look the same size as the full moon as seen with the naked eye. This is understandable because you're enlarging its image with magnification. If I had a 2000x eyepiece I could make Mars look as big as the moon tonight. Sure, the planet would be a blurry mess because atmospheric turbulence would also be magnified, but I could do it. Even when closest to Earth, Mars will always look like a brilliant star to the naked eye. It's just too small to show a disk except in a telescope.
Mars is currently 180 million miles from Earth -- more than five times further than in 2003 -- and looks like a tiny red dot even in a high power telescope. Because it's so far away, it's also not particularly bright, being comparable to the stars in the Big Dipper. Created with Stellarium
Every two years Mars and Earth line up on the same side of the sun which puts them near one another. In 2005, 2007 and early 2010 Mars was near the Earth and bright in our skies. A similar close approach to the one in 2003 will happen again in 2018, but we'll have to wait until 2287 to squeak past 2003's record. If we still have an Internet then, the goofy e-mail circulating today will once again be closer to the truth.
Close approaches of Mars and Earth from 2003 to 2018. The reason Mars' distance from Earth varies every two years is due to its orbit, which is more elliptical (oval) than Earth's. The sun is "off to one side" for planets with more highly elliptical orbits. As Earth comes round to meet Mars, it's a little farther or closer to us depending on where it is in its orbit at that time. Illustration: Bob King
Tonight through August, Mars will be a rather dim "star" low in the western sky during twilight. That doesn't mean it's worth ignoring. In a telescope maybe, but not with the eye or through binoculars. Tomorrow I'll bring you up to date with some fun events involving the Red Planet later this week.
Here's a couple photos from last night's moonrise and this morning's sunrise. Hope you got to see either, or better yet, both.
The full moon rises over Lake Superior within the grey band of Earth's shadow. Photo: Bob King
One sphere gives way to another. Lyle Anderson of Duluth captured this morning's colorful sunrise from his home along the shore of Lake Superior.