Sky Map (Star Chart): July 2018

Printable Star Map

Jeff DeTray from AstronomyBoy.com
Sky Map July 2018

Look up with the July 2018 sky map to navigate the stars and constellations in the night sky. On this page is both a color sky map and a black and white printable map to bring outside!

Click-and-Print Sky Map

Just click here or on the image below to open the printable map—then bring outside!

July printable sky map

 

July’s Sky Map Highlight: Looks Can be Deceiving

The Summer Triangle

Year after year, century after century, star gazers have celebrated the return of the Summer Triangle. At this time every year, the stars Vega, Altair and Deneb form a distinctive three-cornered pattern, high in the southeastern sky.

The three stars are similar in brightness.

Vega

Vega in the constellation Lyra the Lyre is the brightest of the trio and the 5th brightest of all stars. In Carl Sagan’s novel “Contact,” Vega is the source of the first message ever received from an alien civilization. In the movie version, Jodie Foster seeks the source of the Vega message. Back in the real world, we’ve yet to hear anything from the possible inhabitants of the Vega system, but researchers are listening to Vega and thousands of other stars every day, just in case.

Altair

Altair, in Aquila the Eagle, is another Hollywood star, as well as a star in the night sky. In the 1956 film “Forbidden Planet,” a world in the Altair system is home to the relics of an ancient alien civilization and to an eccentric Earth scientist and his beautiful daughter. Altair is the 2nd brightest member of the Summer Triangle 13th brightest star of all.

Deneb

Number 3 in the Summer Triangle and 20th brightest star overall is Deneb, which marks the tail of Cygnus the Swan. Alas, Deneb has never starred in a major motion picture, but it has other claims to fame. Whereas Vega and Altair are relatively close to us in astronomical terms—25 and 17 light-years respectively—Deneb is much farther away, an estimated 2,600 light-years from Earth. A light-year is the distance light travels in one year, a big, BIG number!

Which Star is Brightest?

The three stars of the Summer Triangle appear to be about the same brightness. Put another way, their “apparent brightness” is roughly equal. But looks can be deceiving. We now know that Deneb is more than 100 times more distant than Vega and Altair, yet it appears nearly as bright. How can this be?

The only way Deneb can both be farther away yet appear equal in brightness is if its actual or “intrinsic brightness” is much greater than the others. In fact, Deneb is one of the most luminous of all stars, an astounding 200,000 times brighter than our Sun. The light we see from Deneb left the star about the time the Pyramids of Egypt were being built.

July 2018 Sky Map

Click here or on image below to enlarge this map (PDF).

skymap_july2018_full_width.png
Sky map produced using Chris Marriott’s Skymap Pro

Other July Sights

Once you’ve spotted the Summer Triangle you can use it to find other sights. The largest and most prominent asterism (unofficial star pattern) associated with the Triangle is the Northern Cross, comprised of the brightest stars in Cygnus. Less prominent, but quite striking, is the perfect little Parallelogram which hangs just below blazing Vega in Lyra. Sagitta the Arrow is a dim but delightful constellation that sits right above Altair. It’s one of the smallest constellations, and it really does look like a little arrow!

Another notable asterism on this month’s map isn’t part of the Summer Triangle, but it’s always a lovely sight. It’s the distinctive Teapot in Sagittarius in the lower right part of the map. While you’re visiting the area, note the planet Saturn right above the Teapot’s lid. To the lower left of the Teapot, you’ll find Mars. Both Saturn and Mars are near their brightest for the year.

See SKY WATCH for more highlights of this month’s night sky!

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