Morning Dance of the Planets

Bus Stop Astronomy

October 2015

Morning twilight on Oct. 20, 2015

While waiting in the twilight at the bus stop, students can watch a slow dance of the planets as October segues into November. Toward the east, brilliant Venus dominates the morning sky. Readily apparent near Venus is distant Jupiter, and faint yet with a reddish hue is Mars. Over the next few weeks the trifecta will change their apparent positions and elusive Mercury quickly drops from view.

Look now while it is still relatively dark before we switch from Daylight Saving Time to Standard Time. In November, the spectacle continues but one hour earlier. In Michiana you'll start off the month with more daylight in the morning hours, so you'll have to get outside one hour earlier (yikes!) to watch the action.

The image with the Prairie Vista Elementary School sign shows bright Venus with Jupiter down and to its left on Oct. 19, 2015, around 7:30 a.m. EDT. By the end of the month, the planets will have swapped positions. A conjunction is when two planets appear to be at their closest.

If you were to look at the planets in a modest telescope, you'd see two sights that changed the world. In 1609, Galileo noticed four dots straddling Jupiter. The dots are actually moons that constantly change their relative positions as the moons orbit the planet. Meanwhile, Venus looks like it is less than a perfect sphere. Galileo discovered that Venus goes through phases, just like our moon. How can that be? Those two observations supported Galileo's assertion that Copernicus was right--the planets orbit the sun.

Keep following the planets in the morning this winter as you wait for the start of school. Notice the moon, too, as it changes phases and position relative to the sun and planets. Science begins with observing, so this is some of the easiest science you can do. No classroom required--you just gotta look up.

You can keep up with This Week's Sky at a Glance from Sky & Telescope magazine or subscribe to the handy Sky Calendar from Abrams Planetarium.

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