»  Vaccine For the Mars Virus

Vaccine For the Mars Virus

Mars at 43 million miles from Earth

Mars at 43 million miles from Earth. Image courtesy NASA and the Hubble Heritage Team (STScI/AURA)

Nearly everyone I know receives annual e-mails about Mars from an anonymous source, but sent to them by friends who could not resist forwarding the message to their entire address book. The e-mail declares that at the end of August, the planet Mars will sit closer to Earth than it has in the past 60,000 years, thereby offering spectacular views of the Red Planet. The commentary proclaims, with liberal use of exclamation marks, that Mars will appear as bright as (or as large as) the full Moon in the night sky.

This Martian hyperbole dates from August 2003, when the message was mildly factual, but vastly over-stated, leading people to believe Mars would be so bright that you might need sunglasses at night while driving. The rapid spread of this information was like some sort of brain info-virus, and led to at least one daily newspaper comic that showed Mars crashing into a home while the husband and wife were indoors, debating how close the planet will come.

Every 26 months, or so, Earth makes a close approach to Mars, as our smaller, swifter orbit overtakes Mars around the Sun. Because both the orbits of Mars and Earth are mildly elliptical, some close approaches between the two planets are closer than others, but by barely perceptible amounts.

So the proximity of Mars to Earth in August 2003, while indeed closer than in the past 60,000 years, was nonetheless no more meaningful than me swimming a hundred yards out from the California coast (instead of my usual seventy yards) and then declaring to the world I have never been this close to China before.

During close approaches, Mars slowly becomes one of the brightest objects in the night sky. But how bright is that? Slightly brighter than Jupiter's average brightness. And not as bright as that of Venus. Yet nobody has ever issued warning statements about the visibility of Jupiter or Venus. In any case, Mars has had a close approach 3,000 times in recorded history, and, of course, billions of times in Earth's history.

Now it's time for you to send this antidote to ail the infected people in your address book.

Apparent size of Mars at closest approach

I have of course received this at least once each year since 2003, and I sent a reply this year discussing it. Part of my reply was a GUESS that the part about "Mars will appear as large as the full Moon to the naked eye" was a misreading of what some astronomer might have said about Mars THROUGH A TELESCOPE looking as large as the Moon to the naked eye... When Mars is around 30" arcseconds) in apparent size, magnifying it 60x (a easonable magnifying power for a small scope) will make it about 30' (arcminutes) through the scope, or about the size of the moon to the naked eye. This opposition, I think it will only be about 18" at closest approach, so a higher power will be needed to do this, about 95x. Rick

Mars email antidote

May I email this to everyone in my addressbook, and ask them to email it to everyone in their addressbook, and ask them to email it to everyone in their addressbook.... ad infinitum? With proper credit, of course! Larry Sessions Denver Twitter.com/NASkies

Of the moon illusion too.

I cannot count the many email and arguments (science lessons) I have had over the GIANT HUGE BIG mars e-mails and discussions. Try and explain that the moon is almost always the same size in the sky no matter where it is. So many misconceptions and fibs. I thank the good science. Craig S Bronx, NY