June 7, 2003
Realistic Expectations for Mars Historic Visit
Perhaps you've heard--late this summer Mars will come closer to Earth than its been in 60 millennia. The red planet will appear larger and brighter than at any time in recorded history. It'll be an astronomical show you won't want to miss.
Now with that being said, let's put this in proper perspective. Between now and the end of August, the hype will intensify, leading to great, and maybe unrealistic, expectations.
Do you recall the 1986 visit of Halley's Comet, the famous comet that comes around every 76 years? It generated great interest and anticipation, but also considerable disappointment.
It's 1910 pass was reportedly spectacular, so expectations ran high for 1986--folks anticipated an equally awesome display. But when Halley put on only a good, but not spectacular, show, many were disappointed.
So that Mars in 2003 doesn't repeat the 1986 Halley experience, let's look at what we can realistically expect this summer.
At 4:51 a.m., August 27, 2003, Mars and Earth will be separated by 34,646,418 miles. According to Italian astronomer Aldo Vitagliano, an expert in orbital mechanics, the last time Mars was this close to Earth was in 57,617 BCE, back when our ancestors presumably were proverbial "cave men."
When seen in telescopes, Mars will appear about half the diameter of Jupiter. For a few weeks it will be brighter than Jupiter ever gets, and second only to Venus and the Moon.
So what can we expect to see? Since neither Jupiter nor Venus will be prominent this summer, the fiery red planet will dominate the naked-eye night sky on moonless nights throughout August and September, blazing brighter than any star.
While binoculars won't add much, telescopes will reveal Mars as a small reddish ball. Any visible surface features will be faint and subtle. Mars' southern hemisphere is now tilted toward us, exposing its southern polar cap which will be prominent through June. But as it's now spring in Mars' southern hemisphere, the white-colored polar cap will partially thaw and grow smaller in July and August. It should still be visible, just smaller.
There are sure to be public Mars-viewing star parties hosted by local astronomy societies, so watch for announcements. And we'll be talking more about Mars, so stay tuned to this column.