Simply equipment modifications
Have you noticed that some astrophotographs have diffraction spikes coming from bright stars? They’re caused by the secondary mirror holder in reflector telescopes. Spiders, as they’re known, can give you nice spikes, but if they’re crooked or uneven, the spikes can look horrible. Here, I’ll show you how to get perfect spikes.
With the Australian Solar eclipse coming in 2028, it’s time to get familiar with solar telescopes. With Lunt telescopes you can see the surface of the Sun using white light, or Hydrogen alpha and Calcium-K filters. These all show different aspects of what’s happening there. If you want to photograph it as well, there are cameras for that too.
Mars opposition is in mid-January next year. But before that happens, Mars is going to enter retrograde motion, where it stops being overtaken by the background stars and starts overtaking them back. Retrograde motion stumped the ancient astronomers and had a hand in stimulating the rise of modern scientific thought.
Inspired by a video of an eclipse of Phobos, Bill wondered about the definitions of moons, planets and asteroids. Why are potato shapes important, and how did Phobos stop being one and start being another?
