Category Archives: Short Questions

Sometimes you have a question that has a simple answer, and you’re not interested in all the extra background info. This page is full of short no-nonsense answers, for researchers on the go. Any extra background info will be referenced by a link. I guarantee, not one single answer will take more than a single paragraph!

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 →

How many moons does Neptune have?

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As of July 2013, we know of fourteen 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 20km across, and is known as S/2004 S1, until … 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 →

What is a neutron star?

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  When a star runs out of fuel to burn, it’s outer layers get ejected into space and it’s core collapses under gravity into a white dwarf.  If the star was really big, more than about 8 times the mass of our Sun, then it continues to collapse, becoming denser and denser until the very atoms themselves are crushed.  The enormous gravitational pressure overcomes the Weak Nuclear Force, so that electrons fall out of their orbit and touch the protons … Continue reading →

What is a white dwarf?

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  Stars go through a number of changes as they pass through different life stages.  If a star doesn’t have more mass than about eight times that of our own Sun, then it will end its life as a White Dwarf.  White dwarfs are extremely small, hot and compact objects, composed of degenerate matter, and are all that remains after the original star runs out of fissionable fuel and ejects its outer layers into space.  What remains is usually around … Continue reading →