Night sky can teach you various patterns of geometry if you look closely. Triangles especially can be easily spotted and related to constellations. Two popular constellations that are recognized as triangles are Triangulum and Triangulum Australe.
This year we are lucky to find another triangle in the summer skies. We are talking about the Jupiter's triangle here. Jupiter in April 2018 forms a triangle with two other bright stars called Spica and Arcturus. The significant difference of this triangle with the other triangle constellation is that one point of the triangle will be a brighter planet instead of a star.
To spot this brilliance, just lay down facing the summer night sky, make sure you look in the east-southeast direction. A rough isosceles triangle of Arcturus, Spica and Jupiter can be noticed. The name Jupiter triangle is biased to Jupiter since it is the brightest of the triangle.
The triangle would appear to point towards the northeast, and will have the yellow-orange Arcturus star (magnitude of 0.1) at its vertex. Spica, will be the apparent bluish star that makes the triangle (magnitude of +1.0) and Jupiter (magnitude of –2.4) will be forming the base of the triangle.
The Jupiter Triangle is reported to be in a state of flux eventually as Jupiter would be slowly changing its position when compared to the stars present in the background. As reported, ever since March, Jupiter is seen undergoing a backward journey, which resulted in its westward shift westward when compared to the background stars.
In the later months of the year, Jupiter will be seen resuming its normal motion, more towards eastwards. This will result in Spica and Jupiter getting farther from each other for the rest of the summer months of the year. From middle of September, Spica would become invisible as it will get immersed in the glow of the sunset glow. Same fate will be seen with Jupiter by November.
Later, in fall-months, Jupiter`s motion will take it far to the east to where Spica will be and will not be able to make a convincing Triangle with these two stars.
Thus, this is the best time to look for the Jupiter triangle, else you have to wait for 2030 to see this again.