We all have heard of the term "dog days," which has a direct astronomical connection to the brightest star in the sky, Sirius, in the constellation of Canis Major, the so-called "big dog" of the night sky.
Sirius is the brightest star in the sky, and during the months of June and July the ancients felt that the close proximity of Sirius (the "dog star") to the brightest star of the daytime (the sun) resulted in the extreme heat of the summer season; hence such sultry days have come to be known as dog days.
If we can have dog days, then why not "cat nights?" There is actually an obscure Irish legend about cat nights that deals with witches changing into a feline form, but there is no astronomical connection whatsoever. [Dazzling Night Sky Photos by Stargazers (April 2013 Gallery)]
However, if you venture outside on these chilly early spring evenings, there are several members of the cat family that can be seen riding high overhead and toward the south as darkness falls.
Leo is king
As the winter stars begin to depart in the west this first full month of spring, the ancient lion Leo dominates high in the southern sky.
Leo is among the most ancient of the constellations, with a backward-question mark curve of six stars in the creature’s head appearing to form a large stellar sickle; a star pattern resembling a large backward question mark. To modern sky-watchers, the sickle outlines the majestic head and mane of a great westward-facing lion.
Blue-white Regulus is the brightest of these stars at the end of the sickle’s handle, yet it is still the faintest of the 21 stars in the first-magnitude category. Regulus is 69 light-years away from Earth, and 110 times more luminous than our sun.
There are many stories regarding Leo. One of these connects him with the sphinx, that famous giant half-lion, half-human sculpture in the desert.
It has been suggested that the sphinx is a representation of both Leo and an adjacent constellation, Virgo. The front half of the sphinx belongs to Virgo while the back end (the lion’s body) belongs to Leo.
Interestingly, both constellations stand side-by-side in the sky and the sun is passing through this section of the sky during the Nile’s crucial annual flooding in August and September.
Leo may also have represented the famed Nemean Lion — a veritable "super lion" that legend said terrorized the Valley of Nemea and was unaffected by ordinary weaponry (such as arrows and spears) due to its impenetrable hide.
Next to Regulus, the brightest star in the sickle is Algeiba, in its curved blade. To the naked eye it appears as a single star, but a moderately large telescope clearly shows it to be one of the most beautiful double stars in the sky. It should really be observed in twilight or bright moonlight to reveal the contrasting colors — one star greenish; the other a delicate yellow. [See the Nearest Stars to Earth (Infographic)]
Eastward from the sickle, there is a right triangle of stars which also belongs to Leo. At the eastern point of this triangle you will find Denebola, marking the tip of the Lion’s tail.
Not catty here …
The Lion is a member of the cat family, but although there are three constellations that represent dogs, there are no cats. Actually, at one time, there was a cat among the stars. More than 200 years ago, some star atlases included Felis, the creation of 18th century Frenchman, Joseph Jerome Le Francais de Lalande (1732-1807).
He explained his choice: "I am very fond of cats. I will let this figure scratch on the chart. The starry sky has worried me quite enough in my life, so that now I can have my joke with it."
Although this celestial feline does not exist today, cat fanciers might be consoled by the fact that along with Leo, there are two other members of the cat family that are well situated and close together in the current evening sky: a smaller lion, Leo Minor (perhaps we could call it the "lion cub?") and Lynx.
Lynx, is one of only two animal constellations that has identical Latin and English names. But unfortunately, it is quite dim and rather hard to visualize.
Johannes Hevelius (1611-1687) a 17th century Renaissance man placed it in the sky. Besides being an astronomer, Hevelius was an artist, engraver, well-to-do man of affairs and a leading citizen of Danzig, Poland.
Interestingly, the old astronomy books and sky charts, which depicted the constellations as allegorical drawings, placed the brightest star of Lynx in the tuft of its tail. Looking at some of those old star atlases, it would seem that our nearby lion cub, Leo Minor, is about to provoke a cat fight by biting Lynx’s tail. Ouch!
In our current time, with light pollution proliferating in so many parts of our modern world, Lynx is a star pattern that likely will never be seen by most modern stargazers.
Even in Hevelius’ time, where the night sky was much darker, finding this big cat was a bit of a stretch. In creating Lynx, Hevelius chose an animal that possesses excellent eyesight.
Yet Hevelius himself openly professed that you would have to have a lynx’s eyes to see it!
Joe Rao serves as an instructor and guest lecturer at New York's Hayden Planetarium. He writes about astronomy for The New York Times and other publications, and he is also an on-camera meteorologist for News 12 Westchester, New York. Follow us @Spacedotcom, Facebook and Google+. Original article on SPACE.com.