Nights are at their longest and days at their shortest in the Northern Hemisphere, and vice versa in the south. Much of the sky as it appears in the far south is occupied by constellations that were never seen by the astronomers of ancient Greece. A bright meteor shower radiates from Gemini in mid-month.
At first glance, this open cluster a itppears as a hazy Cloud, but a closer look reveals several individual stars. Although the cluster is also called the Seven Sisters, normal eyesight shows only about six stars, people with exceptional vision can see several more and binoculars bring dozens of stars into view.
The second-best shower of the year radiates from near Castor, in Gemini, reaching a maximum on December 13th, when as many as 100 bright meteors an hour may be seen. Lower rates of activity occur for several days either side of the maximum.
Cancer represents the crab that, in Greek mythology, was crushed underfoot by Hercules during his battle with the multiheaded Hydra. It lies between Gemini and Leo and is the faintest constellation of the Zodiac; its brightest star, Beta Cancri, is of magnitude 3.5. The Sun is within Cancer's boundaries from July 20th until August 10th.
Points of Interest
A multiple star. Through a small telescope, it is seen to consist of two stars, of magnitude 5.1 and 6.2. A telescope with an aperture larger than about 6 in (150 mm) will show that the brighter component has a much closer companion, of magnitude 6.1, which orbits it every 60 years.
An open cluster, also known as the Beehive cluster or the Manger. (Praesepe is Latin, meaning both manger and hive) It appears as a cloudy patch at the limit of naked-eye visibility - its brightest are of 6th magnitude, and it was known to the ancient Greeks - but binoculars show it as a field of stars more than three times the apparent width of the full Moon. It lies about 520 light-years away. To the north and south of the cluster are the stars Gamma Cancri (magnitude 4.7) and Delta Cancri (magnitude 3.9). In ancient times, these were visualized as donkeys feeding at the manger, hence they are known as the aselli, or asses.
M67 (Open Cluster)
An open cluster. It contains more stars than M44 (Praesepe), but it is farther away from us (about 2,600 light-years) and so appears fainter and smaller.
Gemini is a constellation of the Zodiac, Gemini depicts the mythological twins Castor and Pollux, after whom its two brightest stars are named. The twins sailed with the Argonauts in search of the golden fleece, and they were later regarded by the ancient Greeks as patrons of seafarers. The two stars themselves are not related, though, lying at different distances from us. Gemini sits between Taurus and Cancer, and the Sun passes through it from June 21st to July 20th.
Points of Interest
Alpha Geminorum (Castor)
A remarkable multiple star. To the naked eye, it appears as a single star of magnitude 1.6. A small telescope divides it into a blue-white pair of stars of magnitudes 1.9 and 2.9. These form a genuine binary with an orbital period of about 470 years. Both of these stars are spectroscopic binaries. A wider companion of 9th magnitude can also be seen with a small telescope. This is, in fact, a close pair of red dwarfs, forming an eclipsing binary. The whole six-star family is just over 50 light-years away.
Beta Geminorum (Pollux)
The brightest star in the constellation and among the 20 brightest in the sky, at magnitude 1.2. It is an orange-colored giant, 34 light-years away. The coloration is more noticeable when the star is viewed through binoculars.
M35 (Open Cluster)
M35 is a rich open cluster, just visible to the naked eye and easy to see with binoculars. It appears almost as large as the full Moon. Binoculars or a small telescope resolve its individual stars of 8th magnitude and fainter. The cluster lies nearly 3,000 light-years away.
NGC 2392 (Planetary Nebula)
A planetary nebula. Its bluish disk, similar in size to the globe of Saturn, is visible through a small telescope, but large apertures are needed to detect the surrounding features that lend it the appearance of a face and give rise to its popular names.
This imposing constellation of the zodiac lies between Aries and Gemini. It represents the bull into which the Greek god Zeus transformed himself to abduct Princess Europa of Phoenicia. Zeus then swam to Crete with the princess on his back. The constellation represents the front half of the bull's body - the part visible above the Mediterranean waves. It contains two major star clusters, the Pleiades and Hyades. In mythology, the Pleiades were the seven daughters of Atlas and Pleione, and the cluster is also known as the Seven Sisters; the Hyades were the daughters of Atlas and Aethra. In the sky, the Hyades cluster marks the bull's face, while the red giant star Aldebaran forms the creature's bloodshot eye. The tips of the bull's horns are marked by Beta and Zeta Tauri, magnitudes 1.7 and 3.0. The Sun passes through Taurus from May 14th to June 21st..
Points of Interest
Alpha Tauri (Aldebaran)
A red giant star that varies irregularly in brightness between magnitudes 0.75 and 0.95. Although it appears to be a member of the Hyades cluster, it is actually much close to us, being 65 light-years away.
M1 (The Crab Nebula)
The remains of a supernova that was seen from Earth in AD 1054. Under excellent conditions it can be found with binoculars or a mall telescope, but a moderate aperture is needed to see it well. It is elliptical in shape, appearing midway in size between the disk of a planet and the full Moon. It lies about 6,500 light-years away.
A wide double star in the Hyades cluster. Observers with good eyesight can divide the two stars with the naked eye. Theta-1 is a yellow giant, magnitude 3.8; Theta-2 is a white giant of magnitude 3.4, the brightest member of the Hyades.
An eclipsing binary star of the same type as Algol. It ranges between magnitudes 3.4 and 3.9 in a cycle lasting under 4 days.