You are here

Moon and Antares

March 24, 2011

The Moon follows a bright star across the sky in the wee hours tomorrow: Antares, the "heart" of Scorpius. They rise around 2 a.m., and are low in the south at first light, with orange Antares well to the right of the Moon.

Even though the Moon is close to the scorpion, it's not actually in Scorpius right now. Instead, it's in the next constellation over: Ophiuchus, the 13th constellation of the zodiac.

There was a kerfuffle about the zodiac earlier this year. In an interview, an astronomer was explaining how the constellations have shifted relative to the Sun since they were first drawn thousands of years ago. Because of that shift, the Sun doesn't cross the constellations of the zodiac at the same time of year as it did then.

A lot of people interpreted the remarks to mean that astronomers were getting ready to re-draw the zodiac. That's just nonsense, though. Earth wobbles on its axis like a spinning top. That changes the dates at which the Sun crosses through the borders of each constellation -- a process that never stops.

And the Sun actually crosses 13 constellations, not 12 -- the 13th is Ophiuchus, the serpent bearer. The amount of time the Sun spends in each constellation depends on the constellation's width along the Sun's pathway. So the Sun actually spends more time in Ophiuchus than it does in Scorpius.

So astronomers aren't changing a thing about the zodiac. Mother Nature handles that all by herself.

Script by Damond Benningfield, Copyright 2011


Get Premium Audio

Listen to today's episode of StarDate on the web the same day it airs in high-quality streaming audio without any extra ads or announcements. Choose a $8 one-month pass, or listen every day for a year for just $30.