No Bull — Mars Double-Aligns in Taurus Tonight

Mars shines from Taurus, an ancient constellation that represents the Greek god Zeus disguised as a bull. Tonight, April 3, Mars, Aldebaran and Elnath will form a straight line at the same time the planet, Aldebaran and the Pleiades outline a right triangle. Stellarium

I've had my eye on Mars the past two weeks. The planet is passing through the constellation Taurus the bull, which dominates western sky at nightfall in early April. This zodiac constellation is host to two of the brightest and most familiar star clusters in the sky, the V-shaped Hyades, located 151 light-years away, and the dipper-shaped Pleiades, 444 light-years distant.

Taurus also boasts the first magnitude, orange giant star Aldebaran, which appears to belong to the Hyades but in truth is a foreground star. The bull's fiery eye lies just 65 light-years from us along the same line of sight as the cluster. Straight up from the Hyades, which outlines the bull's face, you'll find two stars representing the tips of the bull's horns — Zeta (ζ) Tauri and Elnath, also known as Beta (β) Tauri. 

I've been keeping track of Mars, anticipating the night it will form a perfectly straight line with Aldebaran and Elnath. I love stellar and planetary alignments and can't resist the sight of three bright celestial objects in a row. There's so much randomness in the starry sky I enjoy when the occasional straight line or right triangle appears. Both happen tonight!

Aldebaran, Mars and Elnath will appear to lie along a line this evening (Saturday, April 3). At the same time, Mars, Aldebaran and the Pleiades make a right triangle. I never did well on geometry proofs when I was a sophomore in high school but am still fond for triangles, parallelograms and polygons wherever and whenever they pop up.

China's Tianwen-1 spacecraft took this amazing crescent Mars photo on March 18, 2021. The orbiting craft was 6,850 miles (11,000 km) away from the planet at the time. CNSA

If your sky is clear tonight, you can look up and enjoy these arrangements, too. Of course, they're temporary. Mars, being a planet, is on the move. If you look again tomorrow night (Sunday) the line will be broken and the magic somewhat less. Use this opportunity to become more familiar with planetary motion and the outline of Taurus, a constellation figure you may not have seen before. 

It's also fun to compare Aldebaran and Mars. Both have nearly the same color (or do they?) and vary fractionally in brightness. Aldebaran's the brighter at the moment with a magnitude of 1. Mars is three-tenths of a magnitude fainter at 1.3. Can you see the difference?

Every time you spend a few minutes looking up, the knowledge gained by observation adds up to a greater familiarity and a deeper appreciation of the greatest wilderness of all — the night sky. 

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