Author Archives: Allen Versfeld

About Allen Versfeld

Allen is an amateur astronomer, an IT professional, a podcaster, a father of five growing kids, a barely competent chess player, and the owner and publisher of the Urban Astronomer podcast and website. He has formerly served as Director of the Astrophotography and Citizen Science sections of the Astronomical Society of South Africa. You can find his personal social media feed on Mastodon!

Using Xrays to study exoplanets

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NASA’s Chandra Xray telescope, orbiting the Earth at a speed of 1.7 kilometers per second, has been pointed at an exoplanet for the first time, giving astronomers their first glimpse of another world at Xray wavelengths. They not only found that the Jupiter sized world has a thick atmosphere, but also discovered a previously undiscovered star orbiting in the same system. The planet in star system HD 189733 was first discovered in 2005 by using the radial velocity method. Unusually, … 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 →

NASA’s IRIS take a look at the Sun’s interior

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Back in July, NASA launched their new Interface Region Imaging Spectrograph (IRIS) spacecraft. IRIS is designed to study one specific level of the Sun’s atmosphere at unprecedented speed and details, in the hope of resolving one of the greatest mysteries in solar astronomy. The answers it discovers will not only improve our knowledge of how the nearest star works, but will also improve our understanding of the Solar Wind, and help us to better predict space weather events that threaten … Continue reading →

Globular Cluster study measures individual star motions

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Astronomers using the Hubble Space Telescope (HST) have managed to track the motions of over 30,000 stars in a globular cluster orbiting the Milky Way galaxy.  Their observations have revealed that there are two distinct populations of stars in the cluster: Those created when the cluster first formed, and a second group that were born a hundred million years later. The team of astronomers, led by Professor Harvey Richter of the University of British Columbia, combined 8 years worth of … Continue reading →

The six tails of asteroid P/2013 P5

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In September 2013, astronomers working with the Hubble Space Telescope (HST) discovered that a newly found asteroid had a comet-like tail. Closer study revealed that the tail was composed of six distinct streams of dust. This was surprising enough, but when they took a closer look two weeks later they were astonished to find that the structure of the system had changed completely. The asteroid drew attention from the start: asteroids are small and distant enough that they only ever … Continue reading →