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Astronomers have discovered that the planet Uranus has a blue ring - only the second found in the Solar System. Like the blue ring of Saturn, it probably owes its existence to an accompanying small moon. Scientists suspect subtle forces acting on dust in the rings allow smaller particles to persist while larger ones are recaptured by the moon. Smaller particles reflect blue light, giving the ring its distinctive colour, the US team reports in Science. All other rings - those around Jupiter, Saturn, Uranus and Neptune - are made up of both large and small particles, making the...

Here is a trivia question: How many planets are visible without a telescope? Most will answer "five" (Mercury, Venus, Mars, Jupiter and Saturn). Some might answer "six" and include the Earth in the mix. Six, in fact, is the correct number, but if you exclude our own world, there is indeed one other planet that can be spied without optical aid: the planet Uranus. This week will be a fine time to try and seek it out, especially since it is now favorably placed for viewing in our evening sky and the waxing moon is not overly bright. Of course,...

The first recorded instance of Uranus being spotted in the night sky is believed to date back to Classical Antiquity. During the 2nd century BCE, Hipparchos - the Greek astronomer, mathematician and founder of trigonometry - apparently recorded the planet as a star in his star catalogue (completed in 129 BCE). This catalog was later incorporated into Ptolemy's Almagest, which became the definitive source for Islamic astronomers and for scholars in Medieval Europe for over one-thousand years... This included English astronomer John Flamsteed, who in 1690 observed the star on six occasions and catalogued it as a star in the...

The case for NGC 2419 as a lonely globular wandering the cosmic void between the galaxies is a romantic and intriguing notion, and one you see repeated around the echo chamber that is the modern web. First observed by Sir William Herschel in 1788 and re-observed by his son John in 1833, the debate has swung back and forth as to whether NGC 2419 is a true globular or—as has been also suggested of the magnificent southern sky cluster Omega Centauri—the remnant of a dwarf spheroidal galaxy torn apart by our Milky Way. Lord Rosse also observed NGC 2419 with...