You are here

Moon and Aldebaran

October 29, 2015

Tracking down a planet in another star system can take some patience. Consider Aldebaran, the bright orange star that represents the eye of Taurus, the bull. It stands close to the upper right of the Moon as they climb into good view in late evening.

In 1993, McDonald Observatory astronomers Artie Hatzes and William Cochran reported the discovery of a possible planet in orbit around Aldebaran. Their work showed that if they were seeing a planet, it was much heavier than Jupiter, the giant of our own solar system.

Inspired by earlier work by Canadian astronomers Gordon Walker and Bruce Campbell, the Texas astronomers measured Aldebaran’s “radial velocity” — its motion toward or away from Earth. Tiny changes in that velocity can be caused by the tug of an orbiting planet. They can also be caused by changes on the surface of the star itself — by magnetic storms that are similar to sunspots, for example.

After their initial study, Hatzes and Cochran kept watching Aldebaran with telescopes at McDonald and elsewhere. They also looked at observations made by others as far back as 1980. So based on more than 30 years of data, they recently confirmed their earlier finding: Aldebaran does appear to have a planet.

The planet is at least six-and-a-half times as massive as Jupiter. It orbits Aldebaran once every 21 months, and it’s as far out as Mars is from the Sun — a big but hard-to-confirm planet orbiting the eye of the bull.


Script by Damond Benningfield, Copyright 2015

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.