Swift Mercury - Catch It If You Can!
Mercury, the smallest and fastest of the planets, may not have wings on its heels like its namesake, but it races around the Sun four times each year and can be a challenge for sky watchers to catch.
Mercury is the most difficult to spot of the five planets visible to the unaided eye. The other four, Venus, Mars, Jupiter and Saturn, are all larger and brighter than tiny Mercury, which is a third the size of the Earth. The larger and more distant planets can be seen higher in the sky and for longer periods of time each year. Mercury's orbit keeps the planet close to the sun, which means we can only see it near sunset or sunrise.
This year, our swift neighbor puts on two good evening appearances, one right now and the other in mid-June.
Finding Mercury gets easier when the planet appears near another solar system object. On February 28, if you have a clear view of the western horizon just past sunset, look for a twinkling object 15 degrees above the horizon. (Fifteen degrees is a little less than the distance of your outstretched hand, thumb to pinkie, held at arm's length above the horizon.) On March 1, a tiny sliver of moonlight, looking like the smallest of smiles, will be visible above the planet. And on March 2, look for a slightly larger, but still very thin, crescent moon shining almost twice the distance above Mercury.
One word of caution, which every astronomer agrees upon, is to never aim your telescope or look directly at the Sun. Wait until after the sun has completely set to look for Mercury. It will be easier to spot as the sky darkens, but look quickly, as the speedy messenger will move below the visible horizon an hour past sunset.
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