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Welcome to spring!! The official start of this season was on March 20th when we reached the vernal equinox. This is the first of two times each year that we have equal time for daylight and nighttime. In addition, this is the midpoint between the longest day (summer solstice) and the shortest day (winter solstice).
LEO heralds the spring. The name LEO is Latin for lion which seems appropriate when you look at this impressive constellation. As the season advances, this large constellation appears higher on the eastern horizon each evening until it reaches its zenith in the southern sky around the beginning of April and marches toward the western horizon as summer begins, then disappears from nighttime viewing. This magnificent constellation has been written about for thousands of years. LEO was seen as a lion by the ancient Sumerians, Babylonians, Persians, Egyptians, Greeks, and Romans. Some believe the Sphinx was built to resemble this group of stars.
LEO’s head and mane form a sickle or backwards question mark. The alpha star (brightest) is Regulus located at the bottom of the sickle. It is one of the brightest stars seen at night. This latin word translates to "prince" or "little king". Regulus appears as a large blue star but in fact happens to be a multiple star system. This system consists of four stars grouped into two pairs. The largest star is 3.5 times the mass of our sun and 150 times brighter, at a magnitude of 1.4. It is 77.5 light years away. It is a young star, only a few hundred million years old. It is a blue-white main sequence star with a temperature of 15,400 degrees Kelvin. Scientists believe it has a white dwarf companion star which has yet to be observed. The other pair of stars are designated Regulus B and C. They appear yellow and are dimmer at magnitude 8.
The beta star of LEO is Denebola, which in Arabic means tail of the lion. This young variable star is about 400 million years old and lies 36 light years away from us. It is 12 times brighter than our sun with a magnitude of 2.14. It has a surface temperature of 8,500 degrees Kelvin.
This constellation is a preview to the VIRGO supercluster which contains a plethora of galaxies. There are six easy-to-find galaxies, five of which are Messier objects. The LEO triplet also known as the M66 group consists of M65, M66 and NGC 3628 which are located under LEO’s hindquarters. They are easy to find. First go to Denebola and move to the next star on the right and look below it. These three galaxies all look very different when you view them under high magnification but they can be seen easily all together with low power. M65 (NGC 3623) is a spiral galaxy about 22 million light years away. M66 (NGC 3627) is another spiral galaxy 36 million light years away. NGC 3628 is the most unusual looking of these three. It appears elongated and has a dark dust lane passing through the middle. This galaxy is 30 million light years away.
The other triple system is not as bright but easily seen in low power telescopes. It is located under the belly of the lion. These are M105, M95 (NGC 3351) and M 96 (NGC 3389). M 105 is an elliptical galaxy with a supermassive black hole. M95 and M96 both are spiral galaxies. There are a large number of fainter galaxies nearby.
Finally, don’t forget to come back to this constellation in November to see the Leonid meteor shower which peaks on the 17th. This is always one of the biggest showers of the year and occurs when our orbit passes through the path of comet Temple-Tuttle.
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