Category Archives: Astronomy

All about astronomy: What it is, how the Solar System works, famous astronomers and more

Enceladus’s geysers caused by Saturn’s gravity

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In 2005, the Cassini spacecraft, which has been exploring the system of Saturn and its satellites since 2004, discovered enormous plumes of water spewing out into space from the satellite Enceladus.  These geysers are so powerful and pump out such enormous volumes of water that they are clearly visible from space.  But until recently, it wasn’t clear where all the water was coming from, or what force was propelling it upwards so violently.The water is expelled from a geographical feature … Continue reading →

What is a globular cluster?

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Globular clusters are clusters of stars, arranged into a sphere. They contain tens of thousands of stars, packed very closely together, so that when viewed from the Earth, their core’s appear as a single glowing mass. Globular clusters are arranged in a vast spherical halo around their parent galaxy. Our own Milky Way galaxy has a little over 150 globular clusters, but larger galaxies can have many more than that. They tend to be very old – at least as … Continue reading →

What is that bright star?

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Dear Urban Astronomer   Thanks for all your interesting celestial tidbits, which my hubby and I enjoy very much. We are just viewers and treasurers of the skies we love so much, not a professional like you! Could you perhaps enlighten us about a very bright star which is currently to be seen approx 30% up from the horizon to the east. When we say to the east, it is where our sun sets during the winter season. The star … Continue reading →

How many moons does Neptune have?

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  As of February 2024, we know of sixteen moons orbiting Neptune.  The largest, Triton, was discovered only 17 days after Neptune itself was found in 1846 and it would be over a hundred years before any others were first seen.  Triton is one of the larger moons in the Solar System with a diameter of 2700km, and orbits backwards around Neptune.  The most recently discovered moon, by contrast, is less than 8 km across. No doubt there are more … Continue reading →

How many moons does Pluto have?

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As of 11 July 2012, we know of five moons around Pluto.  The largest, Charon, was discovered in June 1978, and is closer to its parent in size than any other moon in the Solar System.  In fact, when it was first discovered it was found that the combined mass of the two had thrown out all calculations of Pluto’s size.  Up till then, Pluto was assumed to be much larger than we know it is today.  The next two … Continue reading →