Sky Talk February 2009: Dawn Spectacles

A striking encounter of Jupiter and Mars, followed by another of the crescent Moon with those two planets plus Mercury all lined up in a row, will occur just before dawn above the southeastern horizon this month. Despite the hour and Winter chill, it will be well worth rising early and taking a look at both of these events if sky conditions permit.

Rarely in this column do we showcase celestial events that happen before dawn — especially in the middle of Winter — unless it’s really something special. Well, here are two that are! On February 16th about half an hour before sunrise, look to the east-southeast. Just above the horizon you’ll first see Jupiter — and less than a degree to the right of it and noticeably fainter, the planet Mars. Your Edmund binoculars will intensify the view and help pull the pair out of the brightening sky. A low-power telescope having a field of view of at least 1-degree or more (the Edmund wide-field Astroscan is superb for the purpose) will show both worlds nicely, with the ruddy cast of Mars contrasting with the yellowish-white glow of Jupiter. Also, visible to the unaided eye some 7-degrees to the upper right of the pair will be the normally elusive planet Mercury — which at this time will actually appear brighter than Mars, since the latter is heading to the far side of its orbit and the former is on the near side of its to us.

Then, looking southeast on the morning of February 22nd, again about 30 minutes before sunrise, you will find the very thin crescent Moon to the right and highest in the brightening sky of the planets Mercury, Jupiter and Mars, in that order. Scanning this celestial lineup with binoculars will be thrilling experience! But there’s more. The very next morning at the same time, the Moon will have switched places with the trio, now appearing to the left of them — seemingly having “leap-frogged” over the planets to the other side! Actually our satellite continuously moves eastward in its orbit all the time, but unless there are “markers” like a planet or bright star along its celestial pathway, this pretty much goes unnoticed (other than the fact which everyone knows that the Moon rises later each night as it goes through its phases).

Using a telescope, you’ll also have an opportunity to compare the appearance of the three planets with each other. A magnification of at least 30X is recommended and higher would be preferred. However, all three lie near the horizon, where atmospheric turbulence is at its worst and more power just magnifies it more. Even so, Mercury will appear like a tiny half-Moon. Jupiter will show a nearly-full obvious disk and you may catch sight of its four Galilean satellites if the brightening sky permits. Finally, Mars will look pretty much like a shimmering ruddy-orange blob! But it’s the “big picture” that really counts here — seeing three planets and the sliver-thin crescent Moon all in such close proximity as part of the ongoing celestial show.

–James Mullaney
Former assistant editor at Sky & Telescope magazine and author of five books on stargazing.


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