The Milky Way Galaxy

The Milky Way, the galaxy, which is home to our solar system together with at least 200 billion other stars (more recent estimates have around 400 billion) and its planets, and thousands of clusters and nebulae, including at least almost all objects in the Messier catalogue the galaxies on their own (you could two globular clusters as possible exceptions, how likely they are straight, or have recently been built or are in our galaxy of dwarf galaxies that are currently in close encounters with the Milky Way: SagDEG of M54, M79 and possibly the Canis Major dwarf). See also our Messier objects in the Milky Way page, where details are given for each object, which is part of our galaxy is to do. All objects in the Milky Way orbit their common center of mass, the so-called Galactic Center.

As a galaxy, the Milky Way is actually a giant, as its mass is probably between 750 billion and one trillion solar masses, and its diameter about 100000 light years. Radio astronomial investigations on the distribution of hydrogen clouds have shown that the Milky Way is a spiral galaxy, Hubble-type Sb or Sc. It is our galaxy has a strong component with a hard spiral structure and a prominent nuclear reagion is part of a remarkable camber / Halo component. Decade-long observations have more and more evidence that the Milky Way can also be a bar structure (so it would be Type SB), so that it could be as M61 or M83, and is perhaps best described as SABbc. Recent studies have raised support for the assumption that the Milky Way may even have a central bar pronounced barred spiral galaxies like M58, M91, M95, M109, and thus the Hubble-type SBB or SBC.

The Milky Way belongs to the Local Group, a smaller group of 3 large and 30 small galaxies, and is the second largest (after the Andromeda galaxy M31), but perhaps the most massive member of this group. M31, at about 2.9 million light years, is the nearest big galaxy, but a series of weak galaxies are much closer: Many of the dwarf Local Group members are satellites or companions of the Milky Way. The two closest neighbours, both mentioned above, were only discovered recently: The nearest of all, discovered in 2003, is an almost disrupted dwarf galaxy, the Canis Major Dwarf, the core of the approximately 25000 light years away from us and about 45000 light years Years from the galactic center. Secondly, SagDEG at about 88000 light years from us and some 50000 light years from the galactic center. These two dwarfs are currently in close encounters with our galaxy and in sections of its orbit is also located within the volume ocupied by our Milky Way. They are far ahead of the more conspicuous Large and Small Magellanic Cloud, 179000 and 210000 light years, respectively.

The spiral arms of our Milky Way contain interstellar matter, diffuse fog, and young stars and open star clusters emerge from this affair. On the other hand, the bulge component consists of old stars and contains the globular cluster star clusters, our galaxy has probably over 200 globulars, of which we know about the 150th These globular clusters are highly concentrated in the direction of the galactic centre: From its apparent distribution in the sky, Harlow Shapley to the conclusion that this center of the Milky Way is a large gap (which he overestimated of factors) in the direction of Sagittarius rather close to us, as was previously thought.

Our solar system is within the outer regions of this galaxy, even within the hard disk and only about 20 light years "above" the level equatorial symmetry (in the direction of the galactic North Pole, see below), but about 28000 light years from the galactic center. Therefore, the Milky Way appears as a shining band of the whole sky along this symmetry plane, including the "galactic equator. Its center is located in the direction of the constellation Sagittarius, but very close to the border between the two neighbours constellations Scorpius and Ophiuchus. The distance of 28000 light years has recently (1997) have been confirmed by the data from the ESA satellite Hipparcos astrometric. Other studies published thus have denied this figure and a smaller value of about 25000 light years, based on stellar dynamics, a recent study (McNamara et.al 2000, based on RR Lyrae variables) results in about 26000 light years. These data, if relevant, would not immediately impact values for distances of certain objects in the Milky Way or beyond.

The solar system is situated in a small spiral arm, the so-called "local" or "Orion arm, the only link between the inner and outer next more massive weapons, the Sagittarius arm and the Perseus Arm, see our Milky Way spiral-Structure Side.

Similar to other galaxies, supernovae occur there in the Milky Way at irregular intervals of time. If they are not too strong obscurred by interstellar matter, they can, and have been as spectacular events from the earth. Unfortunately has not appeared since the invention of the telescope (the last good supernova was observed by Johannes Kepler in 1604).

Milky Way pictures are wide-angle field exposures. In addition to the attractive and often colorful, they are often suited to the Milky Way objects (including nebulae and star clusters) in their heavenly surroundings of the field stars. Some fields contain many Messier objects and thus also here:

* Milky Way central region including constellations Sagittarius, scorpion, snake makers and Scutum and map the Milky Way Central Region, by Bill Keel of the University of Alabama
* Milky Way in Sagittarius, including parts of the scorpion and snake-bearer
* Milky Way about M17, M18 and M24