The Milky Way (Important Facts) {Part-3}

THE MILKY WAY IS THE NAME GIVEN TO THE FAINT BAND OF LIGHT that stretches across night sky. This light comes from stars and nebulae in our galaxy,  known as the Milky Way Galaxy or simply as the "the Galaxy". The galaxy is believed to be a barred spiral, with a dense central bar of

The Milky Way

stars encircled by by four arms spiralling outwards and surrounded by less dense halo. We cannot see the spiral shape because the Solar System is in one of the spiral arms, the Orion Arm (also called Local Arm).This is how our galaxy looks like from the Earth.

View of Milky Way from Earth

Our position in Milky Way

From our position, the centre of the Galaxy is completely obscured by dust clouds; as a result, optical maps given only a limited view of the galaxy.

Panoramic Radio view of Milky Way

However, a more complete picture can be obtained by studying radio, infra-red, and other radiation.

The central part of the galaxy is relatively small and dense and contains mainly older red star and yellow stars. The Halo is a less dense region in which the oldest stars are situated; some of these stars are as old as the Galaxy itself (possibly 13 billion years). The spiral arms contain main sequence stars and hot, young blue stars, as well as Nebulae (clouds of dust and gas inside which stars are born). The Galaxy is vast, about 100,000 light years across (a light year is about 9,460 billion kilometers); in comparison, the Solar System seems small, at about 12 light hours across (about 13 billion kilometers). The entire Galaxy is rotating in space, although the inner stars out from the center, completes one lap of the Galaxy about every 220 million years.