сряда, 13 март 2013 г.

Cassiopeia Constellation


Queen Cassiopeia, wife of king Cepheus of Еthiopia, was beautiful but arrogant woman. This led to her downfall. In some sources she was referred as a daughter of Coronus and Zeuxo. The cassiopeia constellation is named after her. It is a constellation in the northern sky. Cassiopeia was one of the 48 constellations listed by the Greek astronomer Ptolemy, and it remains one of the 88 modern constellations today.

събота, 9 март 2013 г.

Spacetime

Bodies with mass curve the spacetime
According the theory of general relativity space and time combine into a single continuum called space time. Objects with mass bend that time. The curvature of spacetime is what we feel as the gravity.

Black Hole

The black holes are the most mysterious objects in the universe. A long time thought to be just a theoretical entity, nowadays it is thought that there is a super massive black hole in nearly every galaxy in the universe.

In the center of a black hole the spacetime curvate becomes infinite. This is called singularity.

Black holes are born due to gravitational collapse of large stars at the end of their life. This happens because the internal pressure of an object cannot resist the objects' own gravity.

The defining feature of a black hole is the appearance of an event horizon. This is a boundary in spacetime through which matter and light can only pass inward towards the mass of the black hole. Nothing, not even light, can escape from inside the event horizon. The event horizon is referred to as such because if an event occurs within the boundary, information from that event cannot reach an outside observer, making it impossible to determine if such an event occurred.

The Milky Way

No it is not a candy. The Milky Way is the dim milky band of stars that arches across the sky. It contains our Solar system. With its 100 000 light years wide radius it is a relatively small galaxy compared to the really giant galaxies in the Universe. It is orbited by two smaller galaxies called the Large and the Small Magellanic Clouds. The Milky way is a barren spiral galaxy.

NGC 6872 - The Largest Spiral Galaxy in the Universe

NGC 6872 is a barred spiral galaxy. Recently it was confirmed to be the largest spiral galaxy in the Universe.

NML Cygni - Largest Star in the Universe

NML Cygni or V1489 Cygni is a red hypergiant star. It is the largest start discovered today in the universe the one that is bigger than the rest at about 1650 times the sun's radius, which is 7.67 a.u. It is one of the extreme luminous supergiant stars. Its distance from Earth is estimated to be around 1.6 kpc, or about 5,300 light-years. This star has a dusty environment surrounding it, and it exhibits a bean-shaped asymmetric nebula which is coincident with the distribution of its H2O vapor masers. It is a semiregular variable star with a period of around 940 days.

Andromeda Galaxy

Andromeda Galaxy



The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years from Earth in the Andromeda constellation. Also known as Messier 31, M31, or NGC 224, it is often referred to as the Great Andromeda Nebula in older texts.

Distance to Earth: 2,538,000 light years
Age: 9 billion years
Stars: 1 trillion
Constellation: Andromeda
Apparent mass: ~1,230 billion M☉
Coordinates: RA 0h 42m 44s | Dec 41° 16.152'