The Summer Triangle
Three stars from three constellations
You can see it with your eyes
Finding it in the sky
When to look
From June evenings until the first days of January, looking high toward the south. In the heart of summer the three stars are almost overhead in the middle hours of the night.
How to recognize it
Look for the brightest star almost straight overhead: it is the first point. The other two are far off but easy to spot, one lower and one to the side, and there is nothing else so bright around them.
The main stars
- VegaAlfa Lyrae
- DenebAlfa Cygni
- AltairAlfa Aquilae
- SadrGamma Cygni
- AlbireoBeta Cygni
To get an idea
Each of the three is the brightest star in its own constellation, and that makes them impossible to mix up.
From a dark place the Milky Way crosses the figure like a pale river between its three points.
Fun facts
These are not in the book: there was no room on paper.
Deneb is more than a hundred times farther away than the other two, and yet it looks as bright as they do.
The Milky Way crosses the figure, with a band of dark clouds that splits it in two.
In the Chinese legend Altair is a cowherd and Vega a weaver, separated by the river of stars.
That story is still celebrated today in many festivals in East Asia and is about two thousand six hundred years old.
The air navigators of the twentieth century called it the navigator's triangle and used it to find their way.
From the southern hemisphere the same three stars are seen in winter, because down there the seasons are reversed.
Test yourself
The first question is the one printed under the QR code, with the answer the book did not give. The other four only exist here.
Question 1 of 5★ is the one from your book
What is the Summer Triangle?
Question 2 of 5
Which are the three stars?
Question 3 of 5
What passes between the three points?
Question 4 of 5
When can you see it?
Question 5 of 5
Who called it the navigator's triangle?
Riddles
I have three points and I am not a constellation: my stars do not even know each other, they live in three different figures. It is your eye that joins them. What am I?
Between my three points flows a pale river made of very distant stars. In an ancient story two of my corners are lovers separated by that river. What am I?
The pilots who flew at night used me as a map, before electronic instruments existed. You find me by looking up on warm nights. What am I?
Try it yourself
From the same spot, but on a night with no Moon and far from lights, see whether a pale band appears between the three points: it is the Milky Way.
Come back to the same figure on a November evening. It will still be there, but moved toward the west: the sky has turned, not the stars.
The words
- zenith
- The point in the sky exactly above the head of the person looking.
- Milky Way
- The pale band of very distant stars that crosses the sky.
Sources: Wikidata (Q1096483), Wikipedia (Triangolo estivo).