3.4 KiB
| name | created_by | created_date | updated_by | updated_date |
|---|---|---|---|---|
| Virgo | skybber | 2022-02-04 20:25:14.473944 | skybber | 2022-02-14 14:38:40.710092 |
The large equatorial constellation of the zodiac, in which the intersection of the ecliptic and the equator lies, and through which the Sun passes from 16 September to 30 October, the time of the autumnal equinox, the moment when summer ends and autumn begins. On the ecliptic it is located between Leo and Libra. Virgo is easily found by the elongated conjunction of the upper right and lower left wheels of the Big Dipper, although only four of its stars are brighter than 3rd magnitude. The constellation is Y-shaped in the sky, with Spica at its lower edge, the star γ Virginis at the bottom of a sort of bowl formed by the stars Porrima, Vindemiatrix, β, δ, η Virginis, and Denebola of Leo. The constellation is best seen in the evening sky from March to August. It peaks at midnight in the first decade of April about 40 degrees above the southern horizon. It contains 95 stars of apparent brightness up to 6mag. It is the largest constellation of the zodiacal constellation and the second largest after Hydra, occupying 0.393 sr in the sky.
The constellation is interesting not only from a historical point of view, but especially from an astronomical one. Because Virgo lies very far from the dense clouds of the Milky Way, we find mainly distant galaxies, or more precisely, a large number of distant galaxies. The explanation is simple, looking between the stars Vindemiatrix and Denebola, at the boundary between the constellation Virgo and the Hair of Berenice, lies the heart of the huge Coma-Virgo supercluster of galaxies, to which the Local Group of Milky Way galaxies belongs. Rich outcrops and belts of galaxies extend across the sky to Centaurus and southeast to the tail of Hydra, as well as northwest to the Hounds and the Ursa Major. The exact location of the centre of this supercluster, is at a distance of about 54 million light years towards the two giant elliptical galaxies M84 and M86. The core is very dense, and in its central part, about 5 million light-years across (12˚ x 10˚ in the sky), we can count about 3,000 galaxies. And these are actually only the largest and brightest members - huge elliptical galaxies and spiral galaxies similar to our own Milky Way or the Andromeda galaxy, because dwarf elliptical and various irregular galaxies may not show up in photos from even the largest telescopes.
So Virgo brings a wide variety of galaxies, distant and less bright objects to our observing program, for which we will need preferably a 250mm or larger telescope. However, some of the galaxies are quite bright, after all, eleven of them are stuck in Charles Messier's famous catalogue. Like this supercluster, or just a small group of galaxies like our Local Group, they are actually the rule rather than the exception in deep dark space. The Coma-Virgo cluster itself is probably the center of a larger cluster of galaxy clusters that surpass all our imaginations. If we look to the other side of the sky from the constellations Virgo and Berenice's Hair, for example towards Whale, Eridanus or Pecus, we can see other, much more distant superclusters of galaxies in a large telescope, or rather, only their brightest members. Clusters of galaxies in Hercules or the Northern Crown are also known.
