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ATLANTIC SKY: Looking for the summer triangle | a life

Glenn roberts
Glenn roberts

Hurray, summer is finally here!

Well, officially it will not happen until June 21, but the weather certainly seems to be more summer than in the past few weeks.

The summer solstice begins at 12:54. ADT on this date, marking the official beginning of summer here in the northern hemisphere (winter in the southern hemisphere). He also marks the longest day of the year and, therefore, the shortest night.

The celebration of the summer solstice has a long history, spanning many centuries and countless world cultures, where ancient peoples used the summer solstice to organize their calendars, determine when to plant a crop and, in general, to celebrate the end of the cold and limiting the weather in winter and in the spring. It is said that the ancient Celts of Europe celebrated the coming of summer, dancing around huge bonfires.

Unfortunately, for most people around the world these days is just another day, and although they mentally welcome his arrival, there are few, if any, major public celebrations. However, in the northern European countries of Sweden, Denmark, Finland and Norway, the summer solstice is still celebrated with large public festivals that often include music and dancing around the Maypole.

In the famous Neolithic circle, Stonehenge in Wiltshire, England, gathers annually, with lots of fun and fanfare, to watch the sun rise above the horizon between two huge Hengi stone monoliths during the solstice.

With the return of summer and summer constellations, a special geometric shape appears on our night sky, which is visible in the night sky at this time of year. The summer triangle, a triangular-shaped asterism, can be formed by combining the three brightest stars Deneb, Vega and Altair in the constellations Cygnus (Cygnus), Lyra (Harp) and Aquila (Eagle), respectively. Look for the summer triangle right above your head on any clear night during the summer months.


  • June 17 – the full moon
  • June 21 – summer solstice; 12:54 pm ADT
  • June 23 – Moon at the apogee (farthest from the Earth)
  • June 25 – the last quarter of the moon

It is located in the star-rich part of the Milky Way of our galaxy – a wide, muddy, scattered band of stars (looking like spilled milk) and dust clouds stretching across the night sky from northeast to southwest (a beautiful sight through binoculars). Vega (mag. +0.03) is located 25 light-years from Earth, with Deneb (mag. +1.25) at 3550 light-years and Altair (mag. + 0.77) by 16.6 light-years. A light year is the distance that light travels through the cosmic vacuum in one Julian calendar year (365.25 days), approximately 9.46 trillion kilometers. It is a measure of astronomical distance, not time.

On the night of June 15/16, the growing moon, Jupiter (bottom left) and Antares (the bright "heart" star of Scorpio – Scorpio bottom right) form a triangle in the south-eastern sky about an hour after sunset. The next evening, the nearly full moon moved to the lower left corner of Jupiter, and the three celestial objects now form a shallow arc across the night sky, and then sit in the south-west before dawn.

On the evening of June 18, the Moon (one full day) and Saturn (just above the Moon) rise in tandem (less than one degree away) in the south-south-east sky. Look for Asterism "teapot" in Sagittarius – the archer on the right. That evening, immediately after sunset, Mercury (currently in the mag. +0.1) and Mars (mag. +1.8) can be seen very close to each other in the west-north-west sky – a great photo operation. On June 23, Mercury reaches the greatest eastern (to the left of the Sun) elongation (the angular distance between Mercury and the Sun, visible from Earth), which requires binoculars to be in the evening gloomy light. Venus (mag. -3.8) continues to rise in the sky from east to northeast about an hour before sunrise to the end of June.

The Algonquian tribes of North America called the full moon in June (June 17) the strawberry moon, because it was the month when strawberries were abundant. European settlers in North America called it the pink moon, the month when most roses bloomed.

Until next time, clear sky.

Glenn Roberts lives in Stratford, Pennsylvania, and from childhood was an avid amateur astronomer. His Atlantic Sky column appears every two weeks. He welcomes readers' comments, and anyone who would like to do this is invited to send him an email at

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