Have you ever seen the smallest planet? No, I don’t mean Pluto. It’s now a dwarf planet. I mean the planet Mercury. If you haven’t, now is your chance.
Of the five planets that can be seen with the unaided eye, Mercury is the most difficult to observe. This is because it is only visible during evening or morning twilight. At certain times each year the viewing geometry does make it easier to find. That occurs this year in late March and early April, or now.
There is an additional help this year, the planet Venus. Mercury lies within 4 degrees of Venus during the first ten days of April. Look for both planets a little north of west about 30 minutes after sunset. Binoculars can be a great help in searching for them in the evening twilight. Venus is the brighter of the two. Mercury will appear a little below and north of Venus.
How small is Mercury? It would take eighteen Mercury’s to make one Earth. Up close, Mercury resembles the Moon. Below is a color view of Mercury taken by the MESSENGER spacecraft during its third and final flyby of the planet on September 29, 2009. MESSENGER goes into orbit around Mercury in March of 2011. For more images, check out the MESSENGER website.