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Mars in 2003

The year 2003 will see several significant events in the sky, but almost certainly the premiere event will be the closest approach of Mars to the Earth in 30000 years (in the past or in the future). Mars will be making one of its closest approaches to the Sun (perihelion) just about the same time when the Earth reaches its greatest distance from the Sun (aphelion). Usually Mars' perihelion and the Earth's aphelion's occur on widely spaced dates but this year they come very close together. As Earth passes Mars, the red planet will be substantially bigger and brighter than normal. If the martian skies are cloudless we should be able to see many details on the surface with our 16" telescope that escape us usually. Unfortunately, there is a potential "fly in the ointment". In recent martian perihelions the Sun extra warmth has caused huge dust storms to rise covering Mars from pole to pole. With little moisture in the martian atmosphere, these dust clouds persist for weeks and months on end. When the Mariner space craft first visited the red planet nothing was visible in the dust, even from a few hundred miles up. Carl Sagan headed the planetary imaging team. As he tells the story, when the four tallest Martian volcanos (more than three times as tall as volcanos on Earth) finally poked through the dust, they appeared as dark marks on the surface. His imaging team promptly named them "Carl's Marks".

The scientific community used to look forward to these near passes with more intensity than they do today. Spacecraft and orbiting telescopes now make examinations which surpass anything possible with an Earth based telescope. Still it is just when scientists are most sure that they have all the details just about settled when nature hands them the biggest surprises. There is no way to tell what if anything will surprise us in this close encounter with Mars.

Mars seems to be the source of more incorrect ideas than almost any other planet. Many people think Mars is the closest planet. However this is not the case. Venus comes much closer to the Earth. The last time we passed Mars there were dire (and totally false) predictions that its excess gravity would cause the Earth's crust to weaken resulting in terrible volcanos. Of course nothing out of the ordinary happened. Generations of astronomers peering through telescopes felt they could make out linear markings on the surface. Schaparelli called these "lines" canali (which mean channels). Well they simply aren't there although in some places twisting bending channels exist which look like dried up riverbeds.

Mars will change dramatically over the next 8 months. I was up early at the YMCA looking up at the conjunction of Mars and Venus. To a trained eye Mars was easy to spot, but when I tried to point it out less than two degrees from Venus no one else could spot it. Venus is currently extremely bright (brighter in fact than all the stars in the sky), but Mars wasn't really that dim. In late August we certainly won't have any trouble seeing the red planet in the night sky. The diameter of its disk will increase almost 6 fold, and the intensity of its light will be more than 60 times its current intensity. At this brightness, Mars will be able to cast a shadow in very dark places. You would be able to see it the daytime except that Mars will set as the Sun rises and will rise just after the Sun sets. Which makes sense if you think about it. In order for the Earth and Mars to be as close as possible, they must necessarily line up with the Sun.

Leslie Coleman
Author:
Leslie Coleman
Entry Date:
Jan 1, 2003
Published Under:
Leslie Coleman's Columns
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