Moon and Aldebaran

The eye of the bull — the star Aldebaran — stares into the Moon tonight. The brightest star of Taurus is to the lower left of the Moon at nightfall. The Moon will move closer to Aldebaran during the night — to less than the width of your finger held at arm’s length.

Aldebaran hosts at least one planet. The star is nearing the end of its life, though, so the planet’s future is bleak.

That shouldn’t be the case for a couple of other planetary systems in Taurus. Their planets are still taking shape.

Both systems consist of an infant star surrounded by a disk of gas and dust. An array of radio telescopes known as ALMA has revealed gaps in both disks. The gaps could be created by the gravitational influence of planets.

HL Tauri is less than a million years old. One model says the gaps in its disk are best explained by a system of three planets. The model says they range from roughly a fifth to a half the mass of Jupiter, the largest planet in the solar system.

CI Tauri is about two million years old. A study this year said it could have as many as four giant planets. Two are roughly the mass of Jupiter, with the other two the size of Saturn. One of the Jupiters is quite close to the star. That’s a bit of a surprise. Astronomers had thought that Jupiter-sized planets must be born far away from a star, then move inward later on. So the planets in Taurus are presenting some interesting puzzles for astronomers to solve.

Script by Damond Benningfield