Skywatch Line for Wednesday, July 13th and Thursday, July 14th, 2016

This is the Dudley Observatory Skywatch Line for Wednesday, July 13th and Thursday, July 14th written by Louis Suarato

The 66% illuminated, waxing gibbous Moon rises at 2:48 p.m., Wednesday. The Moon reached apogee, its furthest distance from Earth during this lunar cycle, at 1:24 a.m., early Wednesday, at the distance of 251,201 miles. At nightfall, you’ll find the Moon in the constellation Libra, to the upper right of Mars. Thursday night, a fuller Moon finds its way to the upper right of Saturn and above Mars. Saturn and Mars are now separated by about 28 degrees. By the end of the month, the two planets will close to within 12 degrees. It was on July 14, 1965 that the spacecraft Mariner 4 provided the first close-up photos of Mars. Mariner 4 was 134 million miles from Earth and 10,500 miles from Mars when it took images of the Martian surface. Jupiter is now low over the western horizon after sunset, and sets about 11 p.m. with the constellation Leo. Venus and Mercury are within 3 degrees of each other, but may be too close to the Sun to be seen after sunset.

One of the easiest constellations to view during the summer is Cygnus, also known as the “Swan”. Cygnus ranks 18th in size compared to the other 88 constellations. Cygnus has many popular components, including its brightest star, Deneb. Deneb is the brightest star in the constellation Cygnus, and along with Vega in Lyra, and Altair in Aquila, forms one of the vertices of the asterism known as the Summer Triangle. Deneb is a pulsating white supergiant star, varying in magnitudes between 1.21 and 1.29. Located approximately 3,200 light-years away, Deneb means “tail”, referring to its position within this constellation. At the other end of the Swan, at its head, is the double star, Albireo. This popular target is a binary star comprised of a bright yellow star and a faint blue companion. The two stars can be resolved using low power telescopes. Cygnus also contains what may be the largest known star in the universe. NML Cygni has a radius about 1,183 times that of our Sun. If it replaced our Sun, its surface would extend past the orbit of Jupiter. As large as this star is, it only has a magnitude of 16.6 and would a very large telescope to view.

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