Is there life elsewhere in the universe? These is one of the most often asked questions we have when looking up at the night sky. As if to give shape to our wondering, Leo the Lion thrusts a question mark in our faces every clear February evening.
Face east and look a little more than two fists above the horizon around 7 p.m. and you’ll spot it. It’s a backwards question mark but unmistakable. The brightest star, Regulus, marks the dot and five stars unfurl above outlining the stroke or curl.
The figure also reminded our more agrarian minded ancestors of a sickle, a short-handled tool with a curved blade used for cutting grain. And since Leo has represented a lion since ancient times, the curl still works as originally intended as the beast’s head. So now you have at least three ways of looking at it, a reminder that there’s always more than one way of looking at anything.
You can simply enjoy discovering the pattern for yourself and leave it at that. But there’s more here. Regulus is a quadruple star 79 light years from Earth. The bright one we see with the naked eye is 3.5 times as massive as the sun and rotates so rapidly — one spin takes just 15.9 hours — that it’s stretched into the shape of an egg. For comparison, the sun’s equatorial regions complete a rotation once every 24.5 days.
Only one of Regulus’ companion stars is easily visible. It shines at magnitude 8.1 about 3 arc minutes (1/10th the diameter of a full moon) to the northwest of the main star. A pair of sharply-focused binoculars might just pick it up, but any telescope will show it near the blazing, blue-white primary.
Algieba (al-JEE-bah), the brightest and most colorful of Leo’s double stars, gleams just 8.5° NW of Regulus. The orange primary star and its companion are separated by just 4 arc seconds (4″), so you’ll need a small scope and magnifying 75x to split them apart. Algieba’s bright at magnitude 2.0 and visible with the naked eye even from the suburbs.
The path taken by the sun, moon and planets across the sky called the ecliptic passes just south of Regulus. The ecliptic marks the plane of Earth’s orbit and is considered the plane of the solar system, since most of the planets orbit very close to that plane. Dust boiled off comets or resulting from asteroid collisions collects in a vast cloud along the ecliptic. Sunlight reflecting off the dust is visible as a faint “thumbprint” of diffuse light sticking up from the horizon at dusk every spring called the zodiacal light.
Directly opposite the sun, at the midnight position in the night sky, sunlight reflects directly off the dust, creating a weak patch of light called the gegenschein along the ecliptic. It’s very faint but visible from a dark, light-pollution-free sky. In in mid to late February, you’ll find it just beside Regulus at the bottom of the question mark. The patch is oval-shaped and about 8° across. Look for it on moonless nights around midnight (1 a.m. when Daylight Saving Time kicks in again) now through March.
Looking in the direction of Leo, we gaze up and out of the thick disk of the Milky Way galaxy, where most of its stars are concentrated. With little between us and intergalactic space — and no galactic dust to block the view of what’s beyond — we can peer millions of light years into the distance to see countless other galaxies and clusters of galaxies. Leo is a rich hunting ground for those who like to travel into deep space with mind’s eye and telescope.
And that brings us back to the central question. With all those galaxies, each comprised of billions of stars and billions of planets, what do you think the likelihood is of finding life beyond the Earth is?