Age of Milky Way

It is extremely complex to define the age at which the Milky Way shaped, but the age of the oldest star in the Galaxy yet exposed, HE 1523-0901, is predictable to be about 13.2 billion years, almost as old as the Universe itself.

This estimate is based on examine by a side of astronomers in 2004 using the UV-Visual Echelle Spectrograph of the Very Large Telescope to calculate, for the first time, the beryllium happy of two stars in globular cluster NGC 6397. From this study, the elapsed time among the rise of the first generation of stars in the entire Galaxy and the first creation of stars in the cluster was deduced to be 200 million to 300 million years. By including the predictable age of the stars in the globular cluster, they predictable the age of the oldest stars in the Milky Way at 13.6 ± 0.8 billion years. Based ahead this emerging science, the Galactic thin disk is predictable to have been formed among 6.5 and 10.1 billion being ago.

Size Milky Way

The stellar disk of the Milky Way galaxy is around 100,000 light-years in diameter, and is supposed to be, on average, about 1,000 ly thick. It is estimated to contain at least 200 billion stars and probably up to 400 billion stars, the exact figure depending on the number of very low-mass stars, which is highly uncertain. Extending past the stellar disk is a much thicker disk of gas. Recent observations designate that the gaseous disk of the Milky Way has a width of around 12,000 ly twice the previously established value. As a guide to the relation physical scale of the Milky Way, if it were condensed to 130 km in width, the Solar System would be a mere 2 mm in width.

The Galactic Halo extend outward, but is limited in size by the orbits of the two Milky Way satellites, the Large and the Small Magellanic Clouds, whose perigalacticon is at 180,000 ly .

Milky Way :View from Earth

The Milky Way galaxy, as view from the Earth, itself positioned on one of the spiral arms of the galaxy, appear as a hazy band of white glow in the night sky arch across the entire celestial sphere originate from stars and other fabric which lie within the galactic plane. The plane of the Milky Way is tending by about 60° to the ecliptic, with the North Galactic Pole located at right ascension 12h 49m, declination +27.4° near beta Comae Berenices. The South Galactic Pole is close to alpha Sculptoris.

The center of the galaxy is in the way of Sagittarius, and the Milky Way then "passes" through Scorpius, Ara, Norma, Triangulum Australe, Circinus, Centaurus, Musca, Crux, Carina, Vela, Puppis, Canis Major, Monoceros, Orion & Gemini, Taurus, Auriga, Perseus, Andromeda, Cassiopeia, Cepheus & Lacerta, Cygnus, Vulpecula, Sagitta, Aquila, Ophiuchus, Scutum, and reverse to Sagittarius.

The Milky Way looks brightest in the way of the constellation of Sagittarius, toward the galactic center. Relative to the space equator, it passes as far north as the group of Cassiopeia and as far south as the constellation of Crux, representing the high inclination of Earth's equatorial plane and the plane of the ecliptic relation to the galactic plane. The fact that the Milky Way divides the night sky into two generally equal hemispheres indicates that our Solar System lies close to the immense plane. The Milky Way has a moderately low surface brightness, making it hard to see from any urban or suburban location suffering from light pollution.