Category: vialactea

Milky Way by Niilo Isotalo

Milky Way

by Niilo Isotalo

The Magellanic Clouds are two irregular dwarf …

The Magellanic Clouds are two irregular dwarf galaxies visible in the Southern Celestial Hemisphere; they are members of the Local Group and are orbiting the Milky Way galaxy. Because they both show signs of a bar structure, they are often reclassified as Magellanic spiral galaxies. The two galaxies are:

  • Large Magellanic Cloud (LMC), approximately 160,000 light-years away.
  • Small Magellanic Cloud (SMC), approximately 200,000 light years away.


Image credit: Primoz Cigler, Joseph Brimacombe,

Ed Dunens and EkantTakePhotos

Stars orbiting the Supermassive Black Hole a…

Stars orbiting the Supermassive Black Hole at our Galactic Center.

This demo shows the observed and predicted orbits of thirteen stars that were used by astronomers at the Keck/UCLA Galactic Center Group to predict the position of a huge black hole at the center of the Milky Way. This data was provided by Andrea Ghez and Jessica Lu.


Milky Way On the shore of Lake Dumbleyung …

Milky Way

On the shore of Lake Dumbleyung


William Vrbasso

This vibrant image from NASA’s Spitzer…

This vibrant image from NASA’s Spitzer Space Telescope shows the Large Magellanic Cloud, a satellite galaxy to our own Milky Way galaxy.

Image credit: NASA/JPL-Caltech/STScI

On this day in 1889 was born the astronomer Ed…

On this day in 1889 was born the astronomer Edwin Hubble!

Edwin Hubble played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology and is regarded as one of the most important astronomers of all time.

Hubble discovered that many objects previously thought to be clouds of dust and gas and classified as “nebulae” were actually galaxies beyond the Milky Way. He used the strong direct relationship between a classical Cepheid variable’s luminosity and pulsation period (discovered in 1908 by Henrietta Swan Leavitt) for scaling galactic and extragalactic distances.


Hubble provided evidence that the recessional velocity of a galaxy increases with its distance from the earth, a property known as “Hubble’s law”, a preliminary version of which was proposed earlier by Georges Lemaître. Hubble’s Law implies that the universe is expanding. A decade before, the American astronomer Vesto Slipher had provided the first evidence that the light from many of these nebulae was strongly red-shifted, indicative of high recession velocities.


Hubble’s name is most widely recognized for the Hubble Space Telescope which was named in his honor, with a model prominently displayed in his hometown of Marshfield, Missouri.


Hubble also devised the most commonly used system for classifying galaxies, grouping them according to their appearance in photographic images. He arranged the different groups of galaxies in what became known as the Hubble sequence .

  • Sa (SBa) – tightly wound, smooth arms; large, bright central bulge
  • Sb (SBb) – less tightly wound spiral arms than Sa (SBa); somewhat fainter bulge
  • Sc (SBc) – loosely wound spiral arms, clearly resolved into individual stellar clusters and nebulae; smaller, fainter bulge.

In 1929 he demonstrated that the galaxies move away at great speed and that this speed increases with the distance. The relationship between velocity and distance from Earth is known as the Hubble Law and the ratio between the two values is known as Hubble’s Constant. If a galaxy is approaching, the light shifts to the blue color and if it is moving away from the light to the red color (Doppler effect). In each case, the relative variation of length is proportional to the speed at which the source moves.


Hubble’s law

Hubble’s law is the name for the observation in physical cosmology that:

  1. Objects observed in deep space (extragalactic space, 10 megaparsecs (Mpc) or more) are found to have a red shift, interpreted as a relative velocity away from Earth;
  2. This Doppler shift-measured velocity, of various galaxies receding from the Earth, is approximately proportional to their distance from the Earth for galaxies up to a few hundred megaparsecs away.

When you hear the name “Hubble”, you probably think of the NASA/ESA Hubble Space Telescope. But, decades before the Hubble Space Telescope, Dr Edwin Powell Hubble revolutionised the field of astronomy. In the newest Hubblecast, we take a look at the life and work of this brilliant American astronomer for whom the Hubble Space Telescope is named.

  • Source: wikipedia [1, 2, 3, 4]
  • Image credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)
  • Video:

Is there proof of that the centre of our galaxy is a blackhole?

Probably yes, astronomers believe that practically every galaxy has a black hole in its center, in…

The Andromeda Galaxy Is Coming To Get Us!Credit: Science…

The Andromeda Galaxy Is Coming To Get Us!


Science Channel | Watch the video here 

Astronomy and Astrophysics: Facts

Here is a list of some curiosities of astronomy and astrophysics. From our solar system to…

Supermassive Black Hole Sagittarius A*. Animation of the…

Supermassive Black Hole Sagittarius A*. Animation of the Stellar Orbits around the Galactic Center.

Credit: Keck / UCLA Galactic Center Group