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The Andromeda Galaxy

We live in the Milky Way Galaxy.  The group of galaxies it is in is called the Local Group.  There are around 50 galaxies in the local group, but most of them are small.  The biggest two are the Milky Way Galaxy and the Andromeda Galaxy.  The Milky Way has about 400 million stars and Andromeda has about a trillion.  However, it is possible that the Milky Way has a bigger mass than Andromeda.

Collision Course

The Andromeda Galaxy is heading straight for us at about 500,000 kilometres an hour.  If this sounds frightening, try converting the speed to miles an hour.  Then the speed is only about 320,000 miles an hour.  It sounds less.

We have no way of stopping the collision with our current technology.

Although the collision appears inevitable, there is considerable uncertainty about when it will happen.  NASA estimates that we will collide with the Andromeda Galaxy in about 4 billion years.  The Earth should still be inhabitable at that time so we, if we are still alive, or our descendants should see the collision.


Although a collision between two big galaxies should be spectacular it is not as dangerous as it sounds. Stars and planets will rarely hit each other.  The structure of both galaxies will be disrupted, and in perhaps 5 billion years from now the two galaxies may merge to form a bigger one.  Although the stars and planets will not usually collide the clouds of dust will and a massive new wave of star formation will probably occur.


The Andromeda Galaxy is visible to the naked eye.  Not many galaxies are because of the immense distance from us.  The Andromeda Galaxy is about two and a half million light years from here.   It is the most distant object that can be seen from the surface of the Earth by the unaided Human eye.

People would have seen this Galaxy since prehistoric times, but not had any real idea what they were seeing.  Andromeda was recorded by Abd Al-Rahman Al Sufi in his Book of Fixed Stars written about 964 AD. 

It was after 1917, that the American astronomer Heber Curtis worked out that the object people were seeing was an immense galaxy.

Planets in Andromeda

Because of its distance we are mostly reduced to speculation about the presence of planets round the stars of Andromeda.  There has only been one planet actually photographed and recognised as a planet, but it is reasonable to expect that there are at least billions, and maybe over a trillion, planets in Andromeda.

Life in Andromeda

At the enormous distance of Andromeda we would be extremely lucky if we got any definite indication of life with our present technology.  Life in Andromeda has to be a matter of speculation at this stage.

I would be extremely surprised if there were no life in Andromeda.

Satellite Galaxies

Both the Milky Way and the Andromeda Galaxies have smaller galaxies orbiting them.  The biggest of the Milky Way’s satellite galaxies is the Large Magellanic Cloud.  This was seen on the voyage round the world led by Ferdinand Magellan, and named after Señor Magellan, but it had been recorded at least twice before.  It had been recorded by Abd Al-Rahman Al Sufi in the Book of Fixed Stars in about 964 AD.   It had also been recorded by Amerigo Vespucci.  Neither of these people’s names was used for the galaxy although Señor Vespucci had two continents named after him.











WISE Infrared View of
Andromeda Galaxy and Companions
Picture by NASA
Andromeda Galaxy taken in Ultra Violet.

The irregular shape of the image results when the more than 300 images were assembled to make the final image. Image Credit: NASA/Swift/Stefan Immler (GSFC) and Erin Grand (UMCP).
Gravitational lensing has been used to see planets in the Milky Way, but some Swiss astronomers hope to  find planets other galaxies. They may have found one. A lensing event seen in 2004 is being re-analyzed to see if it actually been caused by a planet 6 times the size of Jupiter in Andromeda.

Amerigo Vespucci