Astronomical Events for August 25th, 2015
Just last month, we made history as New Horizons became the first space probe to visit the dwarf planet Pluto and its moons. When the probe was first launched, Pluto was still a fully-fledged planet and the last time we explored a planet for the first time was on this date, August 25th, in 1989.
The space probe was Voyager 2, the planet was Neptune and it was the last stop in a “Grand Tour” that included Jupiter in 1979, Saturn in 1981 and Uranus in 1986. Until then, no one had ever seen Neptune close-up and in a time before the Hubble Space Telescope, the best images of the distant world were nothing more than indistinct, fuzzy blobs.
Voyager 2 brought the planet into focus and showed us a stunning, deep blue world of white clouds and cyclones. One large, blue eye, reminiscent of Jupiter’s Great Red Spot, stared back at the probe as it sped past at a distance of just under 28,000 miles. Faint, dark rings were discovered encircling the planet, as well as a number of tiny new moons.
Of course, we still have those images to enjoy today, but if you want to view the planet for yourself, you’ll only need a pair of binoculars and a small telescope. But be warned; finding Neptune is not for the faint of heart. Although the planet rises mid-evening and the images above will give you a rough idea of its location, a good star chart or app (such as Mobile Observatory) will help you pick the planet apart from the neighboring stars.
The images above show Aquarius in the south-east at about 11:00 p.m. from the northern hemisphere. Through a telescope at low power, the planet appears as a sky-blue untwinkling star and you’ll probably need a magnification of about 150x to see any kind of a tiny disk. Some might be underwhelmed by the sight, but remember this: as unassuming as Neptune appears, this giant could hold nearly sixty Earths within it and has recorded wind speeds of 1,300 mph.
As you stare at the pale blue dot, remember that it was less than a year later, at a distance of some 3.7 billion miles, that Voyager 1 captured the solar system’s other pale blue dot, caught in a distant sunbeam. The Earth. Our world. The only place we can call home.
Star chart images courtesy of Mobile Observatory. Neptune image credit: NASA/JPL
Events in bold involve objects and/or events that are visible with the naked eye.
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