The Milky Way & Summer Triangle

When you look up at night, with the naked eye, the vast majority of objects that you see are in our galaxy, The Milky Way. Look carefully on a dark summer’s night and you will see a light ‘milky’ band across the sky; you’re looking down the spiral arm of our galaxy. If you can find the constellation Sagittarius then you are looking towards the centre of our galaxy. 

Milky Way






The Milky Way Canon 20D 10mm f3.5 90sec exposure ISO1600 on tracking mount. Dark subtraction ‘On’.





In this image the galaxy centre is off the bottom left corner, partially behind dust lanes; it is thought to be a super massive black hole.

If you place your mouse over the image, labels for 3 stars will pop up; Altair, Vega and Deneb. These 3 stars make up the asterism that is known as “The Summer Triangle”. During summer months in the northern hemisphere this triangle can clearly be seen almost right over head in the middle of the night.

 Our Galaxy is the second largest in our local group ( M31 Andromeda is the largest) and is classified as a barred spiral. In the above image you can clearly see a dark lane of galactic dust. These are observed in many galaxies, as in the below image of our neighbor, Andromeda.



M31 Andromeda – Canon 20D 1500mm f10 21x1min exposures ISO3200 – C6SGT





Super massive black holes are believed to be at the core of many galaxies.  In the chart below I have highlighted the summer triangle in yellow:

Cygnus-chart1 - click for full size Chart produced with Stellarium

Also shown are several notable objects like the Dumbbell Nebula & Ring Nebula which you can read about elsewhere in this blog. Also shown (in red) is Cygnus-X1.

Cygnus-X1 is considered to be a black hole (std not super massive), it was in fact the first object to be widely accepted as a black hole – as such it was the subject of a bet between Stephen Hawking & Kip Thorne. It is a binary system consisting of HDE 226868 (a supergiant star) which is orbiting (and being consumed by) an unseen object of almost 9 solar masses (the black hole).


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