The Constellation Leo
The constellation Leo is one of the original and most interesting of the 88 constellations. Leo, Latin for “lion”, has been depicted in drawings since around 4000BC. In Roman Mythology, Hercules killed the lion as one of his twelve labours.
There is the main constellation Leo and Leo Minor. The latter lies between Ursa Major and the main Leo constellation. Leo Minor is a very similar shape but much more faint.
The shape of Leo shows the crouching Lion and easy to recognise due to the high amount of bright stars that defines it’s shape. The brightest of all the stars is in Leo is Regulus, made up of four stars organised into two binary pairs. At 77 light years from the Sun it is one of the brightest stars in the sky and all four stars can be observed individually through a telescope.
Denebola is at the opposite end of the constellation and means “lion’s tail”. Denebola is a lot closer to us at 36 light years and quite youthful at only 400 million years old. Our own Sun is half way through its life at 5 billion years old.
Tau Leonis, a yellow giant star is furthest away at 560 light years. Even younger than Denebola, at 190 million years old. Tau Leonis has a radial velocity of 9 km/s. In other words, it is moving toward the sun at 9 km/s.
Leo is home to some of the largest structures in the observable universe. The Clowes Campusano Large Quasar Group is a cluster of quasars that measures 2 Billion light years in diameter. Quasars are galactic nuclei powered by a supermassive black hole with a large accretion disk surrounding it.
Leo also has The Cosmic Horseshoe. This is a system of two gravitationally lenses galaxies. The foreground galaxy lies right in front in our line of sight to a more distant galaxy. Due to the light from the background galaxy through the gravity field of the foreground galaxy, the background galaxy's light is lensed by the warped spacetime environment of the foreground galaxy. This is what gives the horseshoe shape.
Leo’s meteor shower is the Leonids shower which peaks annually on the 14th/15th of November. Sadly, it’s another meteor shower that can’t be seen very easily given the lunar cycle and the cloudy autumn nights.
That’s just some of the highlights within the great lion. There are many more other high magnitude stars and even galaxies inside Leo but the limit of what can be written in the blog posts restrict going into detail about them all! Next stop Virgo.