The Scruffy Astronomer

  To be honest, I never thought I'd have the privilege of mucking about with a 5" triplet refractor. I love this job! Introduction The saxon (note the lower case) FCD100 series comes in three sizes, an 80mm, a 100 and the monster 127. It's this last one (www.saxon.com.au/telescopes/ed-refractor-telescopes/saxon-deluxe-127mm-apochromatic-air-spaced-ed-triplet-refractor-telescope.html) I'm talking about here. This is a variant of the scope sold as the Explore Scientific 127ED (https://explorescientificusa.com/products/127mm-fcd100-apochromatic-refractor), however there are a few differences. The focuser on the saxon is the standard barrel-type, where the ES model has a hexagonal focuser, which may be rated to a higher weight limit. First, the basics. This is a five-inch air-spaced triplet apochromatic telescope with Hoya FCD100 ED glass. That sentence alone should have you either bewildered or drooling. Suffice to say, it's a large, high end refractor. Its

About now, Mercury is close to its maximum elongation. This means that, viewed from Earth, it is as far from the glare of the Sun as it ever gets. This is our best opportunity to view the planet. My house is on a hillside facing the west. I look out over a freeway and the Yarra, and I have a good view to the horizon from south-west to north-west. Unfortunately, I can only see it through a double glazed window, so my images weren't going to be great. But the view wasn't the problem. I have to confess here that I'm not the world's keenest planetary astronomer. When I saw something, I didn't really know how I was going to be sure that it was Mercury. After all, it was going to be a dot, at best. You see, Stellarium was telling me that Venus was going to be nearby, separated by about five degrees. Venus would be brighter, lower, and to the left of Mercury. If I saw both planets, it would be easy. But what if I saw only one? How could I be sure it was Mercury,

Lunar eclipse, 26 May 2021 If you're reading this, the eclipse will be long in the past. Don't worry, there will be more soon - a lunar eclipse isn't a very rare event. The lunar eclipse is on Wednesday! On the evening, the Moon rises before entering the Earth's shadow. Because the shadow isn't a sharp line, the start of the eclipse is a bit vague. I'm saying that it begins at about 7:45, although you may have noticed some dimming on one side for some time. The mid-point is something we can be pretty certain of - it's at about 9:15pm. At this point, the Moon will be bathed in red. Why? If you were on the Moon, looking up, you'd see a solar eclipse, with the Sun behind the Earth. But more than that, the Earth would look like a circular sunset. Blue light is scattered by the Earth's atmosphere. Just the red light gets through. My photo here is from a few years ago. This is how I did it - have a go yourself! Shortly before the beginning of

Just a brief one today. Gratulerer med dagen, alle sammen! Idag er det syttende mai - dvs Grunnlovsdag i Norge! Yes, it's Constitution Day in Norway today. Norway adopted its constitution on this day in 1814. On that day the country separated from Denmark. It wasn't a complete victory though, because at the same time Norway was ceded to Sweden. This was part of Denmark's punishment for backing the wrong side in the Napoleonic wars. Norway didn't finally became independent until 1905, when they proudly erased the Swedish flag from their own. Maybe I'm a bit of a Nordophile, but today is also a good opportunity to segue into auroras and the solar cycle. Yes, the Sun is waking up after its mid-cycle nap. Just the other day some weak Auroras appeared and were photographed from Victoria. That's pretty good by Southern Hemisphere standards. Normally they're only seen from the southernmost parts of Tasmania. Auroras are caused by charged par

The imaginary point As we all know, the Earth rotates on its axis. This is why we see the sun rising and setting, as well as the stars moving through the night. But this gives astronomers a challenge. If you have an equatorial mount, it has to be parallel to the Earth's rotation. The more accurate the alignment, the better the mount will perform. Once aligned, you only have to move one axis has to follow a star accurately. The other one can stay still. If the mount is poorly aligned, you'll have to adjust the declination axis occasionally. Of course, this isn't a problem for visual observing. But for photography, a small polar error will ruin your photos. How can you get an accurate alignment? Geometry! I use a computer program called SharpCap to help with my polar aligning. This needs a computer and a camera on the scope. A PoleMaster does pretty much the same thing. SharpCap is very clever. It takes a photo of the polar area, you rotate the RA axis and it take

The Tianhe-1 is the first part of the new Chinese space station. If you like, it's an orbiting foundation, but more accurately, it's called a "core module". At 16.6 metres in length and 22.6 tonnes, it's big already, but it'll grow as the Chinese Space Agency adds modules. It's got several docking ports to allow expansion as well as providing parking space for service vehicles. It was launched on 29 April on top of a Long March 5B heavy-lift rocket. The launch went well and the upper stage of the Long March rocket reached the planned orbit. After dropping the payload, it was probably meant to restart and slow down. This way it would fall back to Earth not far from the launch point. This didn't happen, and the 21 tonne rocket remained in orbit, rising to over 240km, and then dipping to about 150km every 90 minutes. The rocket was also tumbling, indicating it wasn't under control. With each dip in altitude, the rocket brushed the upper atmosp

I got a Bird-Jones telescope in for some maintenance the other day. It needed its mirror realigned. It's a bit of a pain to work on because it's got an additional lens in the focuser that disrupts the laser we use to guide the adjustment. What's a Bird-Jones? The Bird-Jones reflector telescope (also known as a Jones-Bird) is a variant of the Newtonian design. These guys look pretty much like normal Newtonian telescopes, with an open aperture at the front, a mirror down the bottom, a flat secondary at the top and the focuser at the side front. So what's the difference? The mirror is a subtly different (and cheaper) shape. A true Newtonian design has a parabolic primary mirror at the bottom of the tube. A Bird-Jones uses a spherical primary mirror. Have a look at my two scribbled diagrams. The first one shows a parabolic mirror. Parallel light rays from a star are coming in from the right, and bounce off the mirror. No matter whether they hit the m

We all remember the debate about whether Pluto was a planet. The IAU came up with some rules that defined what we call a planet or not. According to these rules, Pluto is a "dwarf planet", or possibly a Kuiper Belt Object (KBO) Object. My recollection of these rules was that one stated that for an object to be a planet, it must have cleared out its orbit, dragging them into its gravity well. Pluto failed this definition due to other KBOs such as Orcus and Albion. But Venus has a dust ring - not a ring around the planet like Saturn and Uranus have, but an agglomeration of dust all along its orbit - it looks like a donut around the Sun. We've known about this ring for a little while - it has been observed by a couple of other instruments in orbit, but it's now been photographed by the Parker Solar Probe. The photo puzzled me. " a planet clears out its orbit " Does it? How could Venus have a dust ring and not violate this definition? I went ba