What’s in the sky this month
For ISS passes, the Moon, the planets, comets, meteor showers and Sky Charts for this summer see our Sky Notes page.
Astronomy News July 2020 – David Glass
SpaceX have managed two spectacular achievements very recently. The first (2nd August) was the safe return of the two astronauts who went up to the ISS in Crew Dragon at the end of May. This involved a traditional “splashdown” which we haven’t seen in a while! All went well and the astronauts are safely back on Earth. A full replay of the whole event with very informative commentary is available here (You can use the scrollbar to zoom through the quiet bits!)
The second was the successful “hop” made by Starship SN5 (4th August local time). A single Raptor engine fuelled by liquid methane and liquid oxygen pushed the 60 tonne, 30m tall assembly gradually into the air and brought it down safely again. Some nice clips of the event are here, the second of which shows the leg deployment and the engine in action (although the flames on the side don’t look like they’re supposed to be there)
The assembly included a “mass simulator” on top to represent a payload.
Watch out for further “hops”, and later on a much higher altitude flight! It looks like field-fabricated rockets can be made to work after all.
Supernovae are rare beasts, but if they happen close enough to us then they can be studied in detail to see how they play out. The results can be compared with models, and teach us a lot about the physics involved. A relatively close one happened in the Large Magellanic Cloud (about 170,000 light-years away) in 1987 and is imaginatively called…wait for it…SN1987A.
It’s long been suspected that a small but massive neutron star should have been left at the centre of the event, but nobody had been able to prove it. However, a recent paper shows that a hot dusty “blob” at the heart of the region is likely to be heated by a neutron star (given the equally catchy name NS1987A). Observations were made with ALMA, a multi-dish interferometric telescope in the Atacama desert, Chile (altitude 16,000 ft), the “How ALMA Works” page is useful. This is a great opportunity to study the early evolution of a supernova, and the results of this study confirm a suspicion that the explosion was asymmetric, with more material blasted out in one direction than the other. No doubt more studies are on their way!
There is a lot more on this topic here. In a nutshell, the observations detected a warm ‘blob’ at the expected location of the neutron star. Theoretical modelling indicates that the most likely scenario is that there is a hot (5 million degree) non-spinning neutron star warming the dust.
Nova Reticuli 2020
I know that travel to the Southern hemisphere is challenging right now, but people there can witness a nova (Latin: nova stella or “new star”). This was found by a comet-hunting astronomer. More detailed observations indicate that this object is a “classical nova”. These occur when a white dwarf star is in a binary system with a larger star, and the white dwarf accretes matter from its larger companion. Eventually, the mass of material built upon the surface of the white dwarf reaches a critical mass and undergoes a thermonuclear explosion creating the nova, but crucially leaves the white dwarf intact. Classical novae can therefore happen more than once. A more extreme case is a Type Ia supernova, where the mass buildup causes the whole white dwarf to be destroyed.
Closer to home, the Solar Orbiter mission sent back some remarkable images of the Sun in July. The mission is intended to study the Solar wind and other important topics related to the Sun. These images are taken from the closest distance yet achieved (48 million miles), and were meant to be tests of the instruments. However, the images found numerous hot spots within the Solar corona which are now named “campfires”. These appear to be like Solar flares but are at least a million times smaller. Perhaps this new discovery can help explain at long last how heat energy is transferred to the Solar corona, which is a region above the visible photosphere (at 5,800 K) but is at a temperature of over a million Kelvin. This problem has baffled Solar physicists for a long time! An animation of the observations is here:
The observations are at extreme ultra-violet wavelengths (17 nanometres), associated with very hot material at around 1 million Kelvin.
Who is and isn`t going to Mars? – Richard Rae
Why have there been so many missions to Mars over the last few weeks?
I don’t know about you, but I have noticed throughout the summer there have been numerous missions to Mars announced on the media; a bit like buses, none for ages then several come around the corner all at once!
Let’s have a look at the recent missions and why there has been a spate of Martian orientated activity this July. Also, we will discover some rovers missed the bus completely and we will answer the question; how many years have elapsed since the Curiosity rover landed on Mars?
What does this image tell us?
Once every 26 months, the Earth and Mars are positioned in their respective orbits in such a way that it reduces the travel time and minimises fuel spent, allowing spacecraft to travel to Mars in roughly 6 months. In the diagram above you can see Mars is playing catch-up as the spacecraft move outward toward the orbit of the red- planet. The last few weeks have therefore been the optimal time for launching missions to Mars.
Nasa and China are sending roving vehicles to the planet this summer. The United Arab Emirates have also launched a mission to Mars. However, the European Space Agency`s (ESA) mission consisting of its rover named Rosalind Franklin has been cancelled.
In March this year the ESA project was called off due to further testing requirements of both software and hardware. The ESA project ExoMars mission (Exobiology on Mars) jointly with Roscosmos (the Russian space agency) is simply postponed for a further (as you have now guessed) 26 months. The project is now named ExoMars 2022.
Here is Dr Anna Nash AIT & Contamination Control Engineer holding up the ESA Pan-Cam at its working height, after giving a bio-safety lecture at Astrofest this year. (Ok it’s not the actual rover camera but an engineering model)
Curiosity is the current rover that Nasa has on Mars.
Curiosity landed on the surface of Mars eight years ago; I had to double check this date I cannot believe that it was that long ago. It has travelled 14 miles on the planet, drilling 26 rock samples along its way. The data Curiosity collects is helping to picture how the Martian climate changed over millions of years and why all the streams have dried up. There are globally over 500 scientists involved in this project so I am sure you can see the interest in getting a larger more sophisticated rover onto the planet’s surface.
Curiosity will shortly be joined by the Perseverance rover, so another sky crane landing is destined to take place in February 2021. You can follow the mission (simply named Mars 2020) from here including real-time flight telemetry, and a Helicopter is included…
Ingenuity is the name of the helicopter that will travel with Perseverance to Mars. Primarily this will be a demonstration of technology mission attempting the first autonomous powered flight on Mars. Many further details of this amazing development are available.
UAE first inspiring mission to Mars
The United Arab Emirates successfully launched the Hope probe from Japan. The UAE engineers assisted by American scientists have produced a sophisticated satellite in just 6 years. This will orbit Mars and investigate the planet’s atmosphere. https://www.bbc.co.uk/news/science-environment-53394737
Launch of Hope on July 19, 2020 from Japan’s Tanegashima Space Center on a Mitsubishi H-IIA rocket. Credit: Mitsubishi Heavy Industries
Chinese Mission Tianwen-1 a most comprehensive mission
Finally, the Chinese have a mission named Tianwen-1 that will include a lander an orbiter and a rover. This combination of craft including 13 scientific payloads, has never been attempted before. If successful it will herald a major technological breakthrough. The aims here are to extensively survey the entire planet with the orbiter and to send the rover to areas of high scientific interest. See here.
There is a short article in Nature regarding this ambitious mission. So, you now have an overview of the missions on their way to Mars, I am sure 2021 will be an exciting year in the exploration of the red planet. Keep checking the mission web pages to keep up with developments
Stellar signposts News – Ian Bradley
As the skies are now getting darker in the evening, it is worth refamiliarizing yourself with the layout of the sky to help you find interesting objects. My constellation navigation skills are not that good having, for many years, used GoTo telescopes. If like I do, you generally observe from one place, in my case my backyard, you also develop intuition as what major constellation are about and where they are. But when you go to a new place…
Until the advent of laptops and planetarium software, my default star atlas was Norton’s Star Atlas. It has clear charts of stars down to magnitude 6.5 and many interesting objects – Messier objects, variable stars and double stars for example. It also includes concise information on many astronomical terms and concepts so the atlas is a useful astronomical quick and simple reference document. For star charts, The Cambridge Star Atlas does a similar job although personally I prefer Norton’s.
With smartphones, there are many apps [SkySafari, Stellarium…] to tell you what is where [especially so if your phone has a GPS and compass built in], and provide information on objects but the small screen size is very limiting.
So, what are the alternatives? It’s dark, your mobile is low on power… We come back to the stars themselves. For the beginner, identifying a few of the major constellations can provide great signposts to less familiar ones, and from them to that small faint fuzzy nebula…
The first thing we have to do is orient ourselves correctly. We are lucky in the northern hemisphere to have a star close to the celestial north pole. At magnitude 2, although its brightness varies between 1.86 and 2.14 over a 4-day period, it is relatively obvious and although not particularly bright, there are no bright stars round about it that can lead to confusion.
Stars rotating around the north celestial pole – a 38-minute exposure from Kendal looking along the River Kent. Polaris is the obvious bright star just below the centre of rotation.
The easiest way to find Polaris is to spot the asterism of the Plough (aka The Big Dipper or The Saucepan) in Ursa Major. This is circumpolar and so always visible. It is fairly unmissable and once you’ve tuned in on its shape, you can recognise it even when much of the asterism is covered by cloud. The two stars at the side of the saucepan are known as The Pointers. Once you’ve found The Plough, finding Polaris, and thus north, is easy. Just follow the line of the two pointer stars away from the bottom of the saucepan, and you come to Polaris.
Bear in mind that at different times of the night, the saucepan will be oriented differently. Twelve hours later than the time in the graphic, the saucepan is ‘upside down’ and you have to follow the pointers down to get to Polaris.
The Plough is a great signpost to other constellations too with the advantage that it is always visible, that is circumpolar, from our latitude.
It is fairly straightforward from The Plough to find Arcturus in Bootes from the curve of the saucepan handle, the tail of the bear, and if you continue the curve, you will come to Spica in Virgo. Along the line opposite to the pointers gives you Deneb in Cygnus in one direction and Regulus in Leo in the other. One diagonal points to Gemini and the pan top to Capella in Auriga.
Cassiopeia is another obvious constellation which can help you navigate, and again has the advantage of being circumpolar. The obvious W of stars open towards the pole star is familiar to most of us.
Finally, although it won’t really be visible until rather late in the evening in the autumn months, there is the magnificent Orion.
I hope this will help you to quickly find your way around. Once you’ve found the major constellations, you can then, in conjunction with your favourite star chart or app, find the less obvious ones. Good luck.
Right-angle polarscope viewer – Ian Bradley
Following on from David Glass’s suggested project in last month’s newsletter, I can report that I tried it.
I had a Canon Right Angle Finder C in my loft. I bought it many years ago when I was imaging with my Canon 400D on my Meade 8” telescope and frankly, I was unimpressed by its usefulness, hence its sojourn in my loft!
I was thinking of trying David’s project as polar aligning was always a pain, metaphorically and physically. Too many times awkwardly peering through a polarscope. On looking to source a right-angle finder, the penny dropped that I had one in the loft.
I used it to polar align my Skywatcher Adventurer tracking mount – see the picture of Comet Neowise later on in the newsletter. I subsequently needed to add more of the furry side from a velcro strip as it didn’t fit snugly enough. I made another minor modification to the design in David’s article – my finder had four tiny screws attaching the scope to an adaptor plate that fitted my camera eyepiece. The adaptor made a perfect template to drill the four small holes in the film canister, so that’s what I did.
Would I do anything differently if I did it again?
Yes. I started the large hole in the end of the film canister with a largish drill and then cut it to get the correct clearance. The plastic tends to deform when drilling and the following cutting is so hit and miss. Instead, I’d use a hot soldering iron, or similar, to melt the plastic and create a much tidier and better fit.
Thanks David – hopefully I’ll have less cricked necks now.
Sharp eyes readers will spot that this is a different image from that in the last newsletter – the editor apologises for the wrong photograph!
Comet Neowise from Kentrigg, Kendal, July 19th, 23:43. Canon EOS 750D, 77mm ISO800 4 x 1min at f4. Camera on a Skywatcher Adventurer tracking mount – its first use. Individual images aligned on both stars and comet and then stacked and combined.
Despite light pollution from Burneside, both the bright dust tail and the faint ion tail are visible. Credit: Ian Bradley