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Skywatching

Close encounter with Mars

"No one would have believed, at the end of the 19th Century, that human affairs were being watched by ..... intellects vast, and cool and unsympathetic, regarding this Earth with envious eyes, and who slowly and surely drew their plans against us...."

This is how H.G. Wells began his book War of the Worlds. The intellects in question were those of the Martians, sitting on their drying, cooling world and thinking a move to somewhere wetter and warmer would be in order.

In Wells' story, the invasion happened when Earth and Mars were passing close to one another. These close encounters are the best times to observe the Red Planet, and we are having one of those encounters now.

These evenings we see Mars in our skies overnight. It is bright, red, and shining steadily, like a lamp, not twinkling.

Earth is the third planet out from the Sun, and Mars is the fourth. Since planets closer to their stars have to move faster in their orbits, and in addition have further to travel than planets further out, the Earth overtakes Mars on the inside track every 26 months.

Since at that moment Mars, Earth and the Sun are in line, with Mars on the opposite side of the Earth from the Sun, we say that Mars is in opposition. Since Mars' orbit is a bit elliptical, and Earth's is too, but less so, some oppositions are closer than others.

If Mars is at the point in its orbit closest to the Sun, and Earth at its most distant point, the two planets can be really close. The encounter in 2008 brought the two planets to around 57 million kilometres of one another, which is almost as close as it gets.

This time round the closest we will get, in mid-October, will be about 61.5 million kilometres. Considering that some oppositions might have the planets passing at a distance of over 100 million kilometres, our current opportunity to observe Mars is worth taking seriously.

We won't have another encounter as good as this until 2035.

Mars can be a tantalizing object to observe. At the moment even a small telescope will show Mars as a reddish-orange disc, a desert planet.

The main impediment to getting a really good view of the planet is turbulence in our atmosphere, making the planet look like a coin at the bottom of a stream. Fortunately, during this encounter, Mars gets quite high in the sky, which reduces the effect of the turbulence.

Those hazy, anti-cyclonic days, where the stars don't twinkle much are the best. However, the key is patience. Amidst the flashing and rippling, there are occasional moments of steadiness that allow us to see the planet in much more detail.

The challenges in getting really good views of the planet are the probable cause of one of the great misunderstandings about Mars, one that persisted until as recently as the 1960s. This was a consequence of staring too hard, for too long, under poor observing conditions.

In 1877, Italian astronomer Giovanni Schiaparelli reported seeing irregular lines on Mars: naturally occurring channels.  Of course, he used the Italian word for channels, canali.

English speaking astronomers mistranslated this word as canals, artificial waterways, made by Martians for water management on their drying planet. American astronomer Percival Lowell built an observatory at Flagstaff, Arizona, just to map the Martian canals. He worked hard, stared hard and worked long hours, and mapped the canals.

It was probably Lowell who launched our obsession with Martian invasions and other stories about Mars.

Of course, the great irony is that in the end, we invaded Mars.  We have sent more spacecraft there than to any other planet. One day there will be intelligent beings on Mars — probably us.

  • After dark, Saturn and brilliant Jupiter lie low in the south
  • Mars is rising in the east at the same time.
  • Venus, even brighter, rises in the early hours.
  • If you have a telescope, all these planets are worth a look.
  • The Moon will be New on the 16th. 

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.



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About the Author

Ken Tapping is an astronomer born in the U.K. He has been with the National Research Council since 1975 and moved to the Okanagan in 1990.  

He plays guitar with a couple of local jazz bands and has written weekly astronomy articles since 1992. 

Tapping has a doctorate from the University of Utrecht in The Netherlands.

[email protected]



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The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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