Look to the east after sunset—especially during February, March, and April—and you will find this particularly bright constellation.
When to Find Leo
The Zodiacal constellations move around more than the other constellations as the earth rotates because they lie near the ecliptic—which is the path the sun travels across the sky. While northern constellations (like the Big Dipper) spin around the pole in a smaller circle, Leo and his 12 companions fly across the high sky from east to west throughout the night. This means that if you were to look for Leo at exactly 9:30 pm each night, you should be able to find him about 6 months out of the year somewhere in the night sky. It Begins to show up in January/February and each day will be 4 minutes higher or more westward in the sky. Leo sets in July as it begins to make its way behind the sun.
Who is Leo
Leo is Latin for Lion. The story in Greek tradition is that this constellation represents a lion with impervious golden fur and claws that could cut through any armor that was fought and killed by Hercules.
When I look at this constellation, however, I personally like to think of the lion written about in the book of revelation: “the Lion of the tribe of Juda, the Root of David…” There are 13 zodiacal constellations, including Ophiuchus the serpent bearer. That means we have the lion of Juda, which rises in the spring (a time of new life) followed by 12 other constellations, or “disciples.” So there’s some interesting Christian symbolism that stands out to me. God did, after all, create the stars in the heavens “for signs” unto us according to the book of Genesis.
Anyway, let’s talk about where to find Leo.
Where to Find Leo
Leo has a well-known asterism (which is a prominent grouping of stars) called the Sickle; it looks like a backward question mark. It also kind of looks like the mane of a lion. Leo comes after Cancer and Gemini in the night sky. So if you can find them you’re off to a good start. Of course, cancer is hard to see, so you’ll probably be better off just looking for the sickle asterism from the start.
You can also use the Big Dipper because Leo is a little south of the two stars at the end of the dipper’s cup shape. You can draw a line through them to point you towards Leo. You’ll see Leo’s sickle, then a triangle of stars nearby representing the lion’s rear quarters. Compared to the rest of the constellations, I think the shape resembles a lion quite well.
What to Look for in Leo
Stars
Leo is a bright constellation, so it shouldn’t be hard to spot. It has stars similar in magnitude to the Gemini twins Castor and Pollux. When I look for Leo, these two stars stand out the most: Alpha Leonis and Gamma Leonis.
- Alpha Leonis is the brightest star in Leo. The Latin name for this star is Regulus, meaning “Prince or Little king.” It is 77 light-years away and although you can’t tell without significant magnification it is actually a quadruple star system. Regulus is a very bright star coming in at an apparent magnitude of 1.4.
A lower number is a brighter magnitude, with 6.5 being about the dimmest visual magnitude the human eye can see. Sirius, the brightest star in the night sky, has an apparent magnitude of about -1. - Gamma Leonis has a visual magnitude of about 2. It is also named Algieba and is a binary star system. The two stars in this binary pair are at least 170 Astronomical units apart, which is about 4 times the distance between Pluto and the sun. (1 astronomical unit “AU” is roughly the distance from the sun to the earth) There is research from 2009 suggesting that Algieba might have an exoplanet (meaning a planet that is outside our solar system) orbiting its main star every 1,340 days.
- Beta Leonis has a visual magnitude of about 2.1. Its name is Denebola, which is derived from an Arabic phrase meaning “tail of the lion.” It is about 36 light-years away.
As you would expect from its Bayer Designation as “beta”, Denebola is said to be the second brightest star in Leo. I compared the listed magnitudes of Beta and Gamma Leonis—on both Wikipedia and the StarWalk app— and Gamma Leonis is listed as being brighter. Stellarium, however, correctly lists Beta in second place, and gives Gamma Leonis a brightness of 2.2.
Of course, these numbers always vary from source to source, but it’s interesting that both listed gamma as having the brighter apparent magnitude. I wonder if this might be because gamma is higher in the sky as the constellation moves towards culmination, so it can shine through less atmosphere which would otherwise dilute its brightness.
Deep-sky Objects
Last, but not least, deep-sky objects! Leo has at least 5 well-known galaxies that you could potentially spot with a telescope. The amazing deep sky objects in Leo could honestly be a topic for a whole video, so I’ll keep it brief for now:
Clustered in the area of Leo’s hind legs is what’s called the “Leo Triplet.” Here you’ll find three galaxies:
- M65
- M66
- NGC 3628
Two are from Charles Messier’s original sky catalog, and one is listed in the “New General Catalogue” (NGC).
Additionally, found in the area under Leo’s belly lies, not one, but three more galaxies:
- M95
- M96
- M105
These galaxies don’t look quite as close together as the Leo Triplet but are nonetheless just as beautiful. So look for those next time you can get behind a telescope!
Look up, keep learning, and remember to smile!
