GREAT PLANETS MEETING

GREAT PLANETS MEEING - 11 MAY 2011

In a few days, during the second week of this month, four planets come together for a rare gathering in the morning skies. Even as you read this, the planets are shifting across the starry background closing in towards each other in the dawn skies about 20 degrees above the Eastern horizon just before sunrise. Set your alarm clock to wake up early by 5:30 am on 11^th May when Jupiter, Venus, Mercury and Mars will be closest together. The first three planets will be seen within one degree of each other, while the red planet Mars will be about 5 degrees below the triplet.

If you hold your finger at arm’s length, you can cover up about 1 degree of the sky. This means that a whole full moon can be covered up by just half the width of a finger. As a rule of thumb, a one centimeter object placed 60 centimeters is equivalent to 1 degree of angle. On 11^th May, the Jupiter-Venus-Mercury triplet will be separated by about two fingers width, while Mars will be five fingers below.

Jupiter, the giant planet and biggest of all in our solar system, will appear as a very bright dot in the sky to the lower left of Venus, the nearest planet to us. At magnitude negative 3.7, Venus will be extremely bright and 25 times brighter than Jupiter which will be shining at magnitude negative 1.7 magnitude. Mercury, the fast moving planet, closest to the Sun, will be seen to the lower right of Venus. This is the best time to put your eyes on this fleeting planet since it is always close to the Sun and very hard to locate in the bright horizon skies. Its brightness magnitude is 0 (zero) hence 10 times fainter than Jupiter.

Through a telescope, Venus will be seen in a gibbous shape (three quarter full) having just a few months ago, passed through its crescent phase. Since the orbit of Venus is inside that of the Earth, it undergoes phase changes similar to the phases of our Moon. Jupiter is a much more interesting object when seen through a telescope, showing distinctly the parallel cloud patterns on its surface. The four Galilean moons of Jupiter are also easily seen, shifting positions on a line extending along the planet’s diameter. Mercury is rather too small to make out features through a small telescope, but a larger telescope would reveal that it is in its half phase, having just a few days earlier, passed through its crescent phase since the orbit of Mercury is also inside that of our Earth. By the end of the month, Mercury will have shifted lower towards the horizon and turned into a full phase.

Mars is much fainter at magnitude positive 1.6 and hence the faintest of the four planets in the meeting since it at its farthest distance from us. The Venus/Mercury pair will shift lower from Venus and shift lower day by day towards the horizon coming closest to Mars on 22^nd May, setting up the second meeting of the planets.

Go to sleep early to get up early before sunset and wonder at the amazing events set up in the heavens over the next few days of May.

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