EAS Newsletter for April 2020 | Eddington Astronomical Society

What’s in the sky this month

For the moon, planets, Comet C/2019 Y4 (Atlas) and deep-sky objects, see Ian Bradley’s notes, links and illustrations on our Sky Notes page.

Astronomy News – David Glass

A quick round-up of just a few fascinating things that have been publicised during March and early April!

Betelgeuse

Our neighbourhood red supergiant star Betelgeuse has caused quite a stir recently, thanks to a relatively rapid dimming event monitored by (amongst others) the Association of Amateur Variable Star Observers (AAVSO). Is it building up to go supernova? Probably not. At our March meeting, we saw evidence that it is brightening up again. Pop outside when the sun has gone down, and (cloud permitting) you can see for yourself that Orion is looking as it should again.

Thiscomparison image shows the star Betelgeuse before and after its unprecedented dimming. The observations, taken
withthe SPHERE instrument on ESO’s Very Large Telescope in January and December 2019, show how much the star has faded
andhow its apparent shape has changed.

So, what happened? In March we thought that a large puff of dust in our direction had caused the dimming, but the evidence was still a bit sketchy. The apparent shape change is indicative of that. However, new research published in March showed that the “surface temperature” of Betelgeuse was only slightly cooler as a result of the dimming. The surface of a star is not something we could stand on but is where electromagnetic radiation from the body of a star can escape unhindered (and do useful things like warm planets and get measured by astronomers). So, the dimming wasn’t due to Betelgeuse cooling off, and it was business as usual except for something in the way of our line of sight.

An exercise:

Go to the AAVSO website
hover the mouse over data
data access and click on Light Curve Generator v2
type in Betelgeuse as the star name. use the “Select Bands” radio button and tick the box below the green square for V band (you can pick others as well if you wish, like the black circle for plentiful visual estimates)
click on “Julian Day”, and select “Calendar Date” from the drop-down menu
You can adjust the dates plotted. When you’re done, click “Send” – and admire the result!

SpaceX Starship SN3

Hot on the heels of SpaceX Starship SN1 launch and second stage separation (unintentional!), Starship SN3 was put in position for testing. For some great footage of this happening

A live webcam is also available.

Live Webcams

There are some fascinating astronomy-webcams to explore if you’re stuck at home. Here are three to be going on with:

Onboard the International Space Station (ISS), when in contact so keep checking back
Polar Bears International Northern Lights (when dark there) –
ESO’s Very Large Telescope (VLT) live panorama, Paranal, Chile

Satellite and Telescope Models to make at home

If you’ve got access to a printer, it’s easy to get the designs to make some impressive 3D models of your favourite satellites or spacecraft and some ground-based telescopes. Here are some of the designs out there:

Atacama Large mm/sub-mm Array (ALMA) antennae
James Webb Space Telescope (with instruction videos)
Hubble Space Telescope (HST)
Cassini (simple model, there is also an advanced one!) –

There are quite a few others out there – if you go to the home page of a satellite (in Earth orbit) or spacecraft (away from Earth Orbit) and look in the outreach sections, you should find something to build. Send us the photos of what you built!