Western Slope Skies - 3/28/14

Mar 28, 2014

Mars At Opposition

Astronomers use a number of curious words to describe the planets in their orbits, for example, quadrature, conjunction, elongation, and ... opposition.

A planet at opposition is roughly in a line with the Sun and the Earth and is further from the Sun than the Earth.  Simply stated, from the Earth's view, the planet is opposite the Sun.

This means that only the superior planets, i.e. those outside the orbit of the Earth can be in opposition.  Can you name the five superior planets?

A planet at opposition will be visible all night long and will be at its brightest.

On April 8, the planet Mars will be at opposition and will be about 57 million miles from Earth.  This is not the closest opposition between Earth and Mars.  That occurred in Aug 2003, when Mars was only 35 million miles from Earth.

Fifty seven million miles is still quite distant and Mars will appear as a red dot to the naked eye.  Even with larger amateur telescopes, it will be challenging to observe surface detail on Mars.

To find Mars now in preparation for opposition, we will use two bright stars, Arcturus and Spica. 

Find the Big Dipper in the northern sky.  Follow the arc of the handle to Arcturus, then continue on the same line to another bright star, Spica.  Mars will be the bright red dot within a hand's width of Spica.  Mars will be much brighter than Spica.

In 2003, when Mars was closest to Earth, a misinterpretation of information started a  rumor that Mars would be appear to be as big as the Moon.  This did not happen and will never happen, yet the rumor continues to circulate, even when Mars is not at opposition.