Notes on[1]:-Milkyway, Galaxy, Solar System,

 

Notes on[1]:-Virgo or Local Superclusters, Local Galactic group, Milkyway ,Galaxy, Solar System, Earth etc.

A diagram of our location in the observable Universe. (Click here for larger image.)

Virgo or Local Superclusters:-

The Virgo Supercluster (Virgo SC) or Local Supercluster (LSC or LS) is the irregular supercluster that contains the Virgo Cluster in addition to the Local Group, which in turn contains the Milky Way and Andromeda galaxies. At least 100 galaxy groups and clusters are located within its diameter of 33 megaparsecs (110 million light-years). It is one of millions of superclusters in the observable Universe.

The Virgo Supercluster in supergalactic coordinates .

 The nearest galaxy groups projected onto the supergalactic plane .

Local Galactic group:- 

The Local Group is the group of galaxies-

The Local Group is the group of galaxies that includes Earth’s galaxy, the Milky Way. The group comprises more than 54 galaxies (includingdwarf galaxies), with its gravitational center located somewhere between the Milky Way and the Andromeda Galaxy. The galaxies of the Local Group cover a 10 million light-year diameter (see 1 E+22 m for distance comparisons) and have a binary (dumbbell)^[1] shape. The group is estimated to have a total mass of (1.29 ± 0.14)×10¹²M_s.^[1] The group itself is part of the Virgo Supercluster (i.e. the Local Supercluster).^[2]

The two most massive members of the group are the Milky Way and the Andromeda Galaxy. These two Spiral galaxies each have a system of satellite galaxies.

• The Milky Way’s satellite system consists of Sagittarius Dwarf Galaxy, Large Magellanic Cloud, Small Magellanic Cloud, Canis Major Dwarf, Ursa Minor Dwarf, Draco Dwarf, Carina Dwarf, Sextans Dwarf, Sculptor Dwarf, Fornax Dwarf, Leo I, Leo II, and Ursa Major I Dwarfand Ursa Major II Dwarf.
• Andromeda’s satellite system comprises M32, M110, NGC 147, NGC 185, And I, And II, And III, And IV, And V, Pegasus dSph (aka And VI), Cassiopeia Dwarf (aka And VII), And VIII, And IX, And X, And XI, And XII, And XIII, And XIV, And XV, And XVI, And XVII, And XVIII, And XIX, and And XX.
• The Triangulum Galaxy, the third largest and only unbarred spiral galaxy in the Local Group, may or may not be a companion to the Andromeda galaxy but probably has Pisces Dwarf as a satellite.
• The membership of NGC 3109, and its companions Sextans A and the Antlia Dwarf, is uncertain due to their extreme distance from the center of the Local Group.

The other members of the group are gravitationally secluded from these large subgroups: IC10, IC1613, Phoenix Dwarf, Leo A, Tucana Dwarf,Cetus Dwarf, Pegasus Dwarf Irregular, Wolf-Lundmark-Melotte, Aquarius Dwarf, and Sagittarius Dwarf Irregular.

[A member of the Local Group of galaxies, irregular galaxy Sextans A is 4.3 million light-years distant. The bright Milky Way foreground stars appear yellowish in this view. Beyond them lie the stars of Sextans A with young blue star clusters clearly visible.]

Component galaxies

Map

The Andromeda Galaxy

[A view of the Milky Way towards the Constellation Sagittarius (actually theGalactic Center) as seen from a non-light polluted area (the Black Rock Desert, Nevada).]

[Triangulum Galaxy – Messier 33]

Spiral galaxies
name	type	constellation	notes
Andromeda Galaxy (M31, NGC 224)	SA(s)b	Andromeda	Largest member of the group, recently (2006) discovered to also be a barred spiral. May be less massive than the Milky Way.
Milky Way	SBbc	n/a	Second largest, though possibly most massive galaxy in the group.[4]
Triangulum Galaxy (M33, NGC 598)	SAc	Triangulum	Third largest, only ordinary spiral galaxy and possible satellite of the Andromeda Galaxy.

Solar System:- 

The Solar System^[a] consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system’s mass (well over 99%) is in the Sun. Of the many objects that orbit the Sun, most of themass is contained within eight relatively solitary planets^[e] whose orbits are almost circular and lie within a nearly flat disc called the ecliptic plane. The four smaller inner planets, Mercury, Venus, Earth and Mars, also called the terrestrial planets, are primarily composed of rock and metal. The four outer planets, the gas giants, are substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are composed largely of ices, such as water, ammonia and methane, and are often referred to separately as “ice giants”.

The Solar System is also home to a number of regions populated by smaller objects. The asteroid belt, which lies between Mars and Jupiter, is similar to the terrestrial planets as it is composed mainly of rock and metal. Beyond Neptune’s orbit lie the Kuiper belt and scattered disc; linked populations of trans-Neptunian objectscomposed mostly of ices such as water, ammonia and methane. Within these populations, five individual objects, Ceres, Pluto, Haumea, Makemake and Eris, are recognized to be large enough to have been rounded by their own gravity, and are thus termed dwarf planets.^[e] In addition to thousands of small bodies^[e] in those two regions, various other small body populations, such as comets, centaurs and interplanetary dust, freely travel between regions.

[Planets and dwarf planets of the Solar System. Sizes are to scale, but relative distances from the Sun are not.]

[Solar System showing plane of the Earth’s orbit around the Sun in 3D view with only Mercury, Venus, Earth and Mars]

[Solar System showing the plane of the ecliptic of the Earth’s orbit around the Sun in 3D view showing Mercury, Venus, Earth, Mars and Jupiter making one full revolution. Saturn and Uranus also appear in their own respective orbits around the Sun]

Six of the planets and three of the dwarf planets are orbited by natural satellites,^[b] usually termed “moons” after Earth’s Moon. Each of the outer planets is encircled by planetary rings of dust and other particles.

The solar wind, a flow of plasma from the Sun, creates a bubble in the interstellar medium known as the heliosphere, which extends out to the edge of the scattered disc. The hypothetical Oort cloud, which acts as the source for long-period comets, may also exist at a distance roughly a thousand times further than the heliosphere.

The Solar System is located in the Milky Way galaxy, which contains about 200 billion stars.

Courtesy- From Wikipedia, the free encyclopedia

compiled/edited-raf-21.12.2011