3 planets to offer rare visual treat on Sunday

Rise before dawn on Sunday, prepare a thermos of hot cocoa, bundle up, drive to some spot where mountains don't obstruct the eastern horizon — and watch an astronomical grouping not seen since the Civil War.

As the Denver Astronomical Society points out, before dawn the planets Mars, Mercury and Jupiter will be grouped within a 1 degree circle. Mercury, the smallest planet, will seem only 0.1 degree from Jupiter, the largest, the society adds on its Web site, www.denverastrosociety.org/.

Patrick Wiggins, NASA solar system ambassador to Utah and northern Nevada, said the planets should rise in the southeast around 7 a.m. and will be easiest to see before dawn as they rise.

The best place to observe them is a location with a low, flat eastern horizon clear of trees, buildings and other obstructions, he said.

The last time this grouping was seen was Sept. 2, 1861, he said.

The apparent closeness of the planets is only an optical illusion, he said. They happen to be lining up in their orbits with our line of sight. In reality, Mars is four times as far away as Mercury, and Jupiter is four times as far away as Mars.