Basic astronomy and night sky information
The full “Corn Moon” arrives today at 18:35 UTC. This Moon is also a “Super Moon”, appearing 7% larger than an average full Moon. Look for it rising over the eastern horizon after sunset. It makes for a great photo-op, or for a little end-of-summer contemplation as the air turns cooler and the nights grow longer.
The August Full Moon is also called the “Grain Moon”.
(Image credit: Julie Falk)
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Ocean tides are one of the few phenomena that bring the workings of the sky down to Earth. The gravitational pull of the Moon, and to a lesser degree the Sun, tug on the world’s oceans while the Earth rotates under them, causing the ocean to appear to rise and fall twice each day. Isaac Newton applied his theory of gravitation to explain the tides. He reasoned that the Moon pulls on the ocean on the Moon-facing side of Earth, pulls on the Earth itself to a lesser degree because it’s further away, and pulls on the ocean on the far side of the Earth least of all. The effect is to cause the oceans to bulge slightly on a line towards the Moon as the earth rotates. So we see two tides each day spaced by 12 hours plus a little bit more to account for the Moon’s revolution around the Sun. Other than sunlight itself, tides are one of the most familiar astronomical phenomena we see around us.
In this time-lapse video by photographer Alan Dyer, you see the tides in action on the east coast of Canada, including the Bay of Fundy, a place in New Brunswick that boasts the highest tides in the world. It ends with a view of the Moon and Sun setting over the Bay of Fundy.
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One of the best targets for a quick stargazing session this time of year is the pretty but underappreciated open star cluster IC 4665. It’s a snap to find, beautiful to behold, and like most sky sights on Cosmic Pursuits, it’s visible from the northern and southern hemispheres.
IC 4665 is spread out over a full degree, more than twice the diameter of the full Moon, so it looks fainter than its integrated magnitude of 4.7. In dark sky, IC4665 is just barely visible to the unaided eye roughly 1° NE of the star Celebrai in the constellation Ophiuchus. Celebrai, or β (beta) Ophiuchi, is one of the stars in the distinctive asterism called Taurus Poniatowski, the “little bull”. If you’re battling light pollution, you’ll need binoculars to spot the cluster [Read more…] about IC 4665, the “HI” Star Cluster
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Comet 67/P (Churyumov-Gerasimenko) reached its closest point to the Sun on August 14, 2015. It also became the first comet to enter the inner solar system and reach perihelion with a man-made companion, namely the magnificent Rosetta spacecraft operated by the European Space Agency. Rosetta has studied the comet for the past year, dropped the little Philae probe in late 2014 to land on the comet, and now enjoys a close-up view of the comet’s fulminating nucleus as it warms and ejects plumes of gas into space. Two weeks before perihelion, Rosetta captured a spectacular image of a brilliant jet erupting from “neck” of the bi-lobed comet (see above). The jet was the brightest yet seen by Rosetta, and the fireworks lasted nearly 20 minutes [Read more…] about Comet 67/P Springs a Leak at Perihelion
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