Once-in-a-lifetime view of Mars in a couple of weeks? Don't bet on it!
NASA/J. Bell (Cornell University) and M. Wolff (Space Science Institution)
It's b-a-a-a-a-ck – the infamous e-mail trying to entice you to see a close encounter with Mars later this month, one that actually happened six years ago. It won't happen again for another 50,000 to 60,000 years, no matter when you receive the e-mail.
And when it did happen, the vista was a bit more modest than even the original e-mail suggested. Mars appearing as big as a full moon? The only people who will get that kind of view of Mars are the folks looking out the window of a space ship as it makes its final approach to the red planet.
To be fair, one variant of this e-mail said Mars would look as big as the full moon (the moon as seen by the naked eye) if Mars were viewed through a telescope with an eyepiece that magnified the image 75 times.
Even then, the moon would still look bigger because of the optical illusion humans experience that make the moon appear larger than it actually is. Picky, picky.
The date for this alleged upcoming spectacular view: Aug. 27, when Mars supposedly is to swing past Earth at a distance of 34.6 million miles. How far away will Mars actually be in two weeks? Try 152 million miles, give or take a few. Its next-closest approach to Earth occurs in January 2010, when it will be 62 million miles from Earth and begins to widen the gap again.
The e-mail first appeared in 2003, when Mars was, in fact, going to make its closest approach to Earth in many millenniums. But the missive has cropped up several times since. Which means we'll see it again in a year or two.
Some variants talk about Mars appearing as big as a full moon, implying it will look that way to the naked eye. Be skeptical. Very skeptical.
The moon is roughly 2,200 miles across and about 239,000 miles away. Mars is roughly twice as big as the moon. And it's going to be 62,000,000 miles away, nearly 260 times farther away than the moon. Mars appearing full-moon size in our night sky? Not so much. Even at 34.6 million miles away, as in 2003.
And there will be plenty encounters almost as close, so that the "never see it again in your lifetime" phrase is misleading.
That said, the close encounter in 2003 was pretty cool. And it provided a great opportunity to share intimate views of the night sky with interested Monitor colleagues.
Another staff member and I had decent-sized telescopes, by backyard standards. So we e-mailed Mars-night invitations to the staff, set up our telescopes at a nearby Audubon Society reserve, and spent an enjoyable evening sharing views of Mars and anything else we could aim at with the small group that joined us.
Moral of the story: Even an off-the-wall e-mail has some benefit if you let it entice you to take a look at the spectacular – and unhyped – vistas the night sky has to offer to the naked eye, through binoculars, or with a telescope.