The Sky Tonight - April 2022
Orion has nearly finished his long march across the sky, setting in the West just after sunset slightly earlier each day as …Explore
It’s all about the planets this month as Jupiter, Saturn and Venus continue their impressive marches over the sky, visible straight overhead and to the west respectively. The Moon makes its monthly trundle across the sky, adding to the nightly show.
The close relative positions in the sky of all these objects allows for a nice visualisation of the ecliptic – basically the plane of the Solar System in which the planets orbit. Draw a straight line with your finger from the horizon to Venus, through Saturn, and on to Jupiter. Catch the Moon in there as well if you can. This line will give you a good idea of the orientation of the orbits of the Solar System.
A nice alignment on 9 November.
Early November also allows a special viewing opportunity in the stars. To the west, at sunset, you will see the scorpion low in the sky, partially set already, chasing the sun over the horizon. After Scorpius has departed, you can turn around and watch Orion rise in the east. This is one of only two periods in the year when you can see Orion and Scorpius in the sky at around sunset. The other time of year of course is six months from now in May, where it will be the other way round, with Orion setting in the west and Scorpius rising in the east at sunset.
The Leonids meteor shower peaks just before sunrise on the 17 November. If you’re game, you will see Leo in the northeast from about 2am and can expect to see a good number of meteors emanating from here – although this may be inhibited by the gibbous Moon in the west.
Eclipse season is here again, but not a whole lot to see this time round. A partial lunar eclipse takes place on the afternoon (AWST) of 19 November. This is great news for people in the Americas, but hard to see over here. In Australia, the best you’ll get is the end of the eclipse visible in the eastern states. Over here on the west coast, if you didn’t know it was happening there’s a good chance you wouldn’t even notice the penumbral shadow on the moon.
Lunar eclipses happen when the Moon passes through the Earth’s shadow. Two weeks after this there will be the sister solar eclipse on 4 December. Temper your expectations – you won’t be able to see that one either!
The premier public astronomy event of the year, Astrofest, is back! Organised by the Astronomy WA collective, it is making its reappearance on Saturday 13 November after being postponed from March due to COVID. This year’s theme is ‘A Parade of Planets’ as all the above-mentioned planets will be the stars of the show (pun intended) .
Astrofest is a free event for anybody and everybody, and you should definitely save the date and make plans to attend. Be led on a live tour of the night sky, talk to professional astronomers, build a LEGO telescope and enjoy the stage shows!
Find out more on the Astronomy WA website.
After being deployed from the International Space Station (ISS) on 6 October, WA’s first satellite Binar-1 seemed to be off to a good start. But this successful deployment was followed by two nail-biting weeks as people on the ground were unable to receive any communications from the satellite.
They finally detected signals late in the month and are now working hard to get the satellite up to full capacity. It’s on and can receive signals but seems to be distracted (admiring the view probably) and is causing some head scratching for people on the ground.
Image: What a view! Binar-1 is deployed from the ISS, alongside two similar satellites from the Philippines (credit: JAXA).
Binar-1 is too small to be seen from the ground with your eyes, but you can track it down if you are a keen radio enthusiast and it is on a similar orbit to the International Space Station. It has moved quite far from the station’s location by now, but if you can spot the station then know that Binar-1 is treading similar steps as well.
You can use this website to help you figure out the best time to see the ISS passing overhead. If you’re in Perth, then 3 November at 8.21pm is a particularly bright occurrence and worth setting an alarm for. Don’t be late! Satellites in low earth orbit like the ISS and Binar-1 move more than 7km per second.
Bright ISS overpass visible in Perth at 8.21pm local time.
Venus close to Sagittarius A*.
Moon next to Venus.
Venus, Moon, Saturn, Jupiter in pleasing alignment.
Moon next to Saturn.
Moon next to Jupiter.
Leonids meteor shower before dawn.
Venus is looking glorious in the western sky in the evenings. Because of the way the orbits line up , it is backdropped by the centre of the Milky Way in Sagittarius right now, and in the first week of November its path will take it almost right through the middle, as seen from Earth.
On 4 November it will be extremely close to Sagittarius A*, the black hole at the centre of the Milky Way. This is of course an observational effect, the black hole itself is 26,000 light years away, but you can use Venus as a reference point.
You can also take the opportunity to use the stars of Sagittarius to make ‘the teapot’ (shown here outlined in green), which will help guide you. If the teapot asterism feels a little forced, it’s nothing compared to the centaur that it is supposed to represent.
Venus in Sagittarius on 4 November
Jupiter is still looking nice and bright, high in the evening skies. It reaches eastern quadrature on 15 November, which means at sunset on this date it will lie exactly along a line drawn north to south in the sky. Seen from above, lines drawn from the Sun to Earth and from Earth to Jupiter will meet at a right angle. Another way of thinking about this is if you point one hand at the setting sun and the other at Jupiter, your arms will make a right angle.
Aries is a medium-sized constellation and part of the Zodiac, meaning that it lies along the ecliptic which you will be able to trace out using the instructions above. It is visible in the northern sky in the mid-evenings during November, and is recognised as the gently curving set of stars representing the ram and its horns.
The brightest star in this constellation is Hamal, a giant star that has used up all the fuel in its core and is now in the process of fusing hydrogen in layers around the middle. The location of fusion away from the core of the star causes its outer layers to heat up and expand, and ultimately cool the star down a little, turning it a reddish colour.
The ram appears in many stories of mythology, perhaps the most well known being the bearer of the golden fleece which was made from its hide, serving as the basis for one of the trials of Jason and his crew of Argonauts. This story is also recorded in the gigantic asterism of Argo Navis, these days broken into the constellations of Vela, Puppis and Carina – visible in the south east at the same time as Aries is up in the north.
Always guaranteed to get a lame laugh, this planet gets its name from the primordial Greek God of the Sky. It’s not easy to see, but you can figure out its rough location by tracing the ecliptic across the sky to its position. In exceptionally dark skies you can see it without a telescope but it’s more likely that you will need some equipment to help you out. It should appear as a greenish-blue source through a medium-sized telescope.
Uranus is technically the first planet ever discovered. The other naked eye planets (Mercury, Venus, Mars, Jupiter and Saturn) have been known since antiquity, while Uranus is recorded as being discovered on 13 March 1781. Interestingly, the planet has a long history of accidental observation by people who didn’t quite recognise it for what it was. Its long orbit and great distance from us mean it requires many observations or powerful equipment to see the signs that this point of light in the sky is an entire world.
Uranus’s large tilt of 97.7 degrees is something of a mystery, with possible explanations usually involving a giant collision with planet sized object long ago. No matter how, the result is that seasons on Uranus last for decades at a time.
Uranus presents an almost featureless face to Voyager 2
The local claim to fame is that observations performed at Perth Observatory helped confirm the discovery of the rings of Uranus. The planet was predicted to pass in front of a distant star and block out the light received. Astronomers noticed that in addition to the expected drop in starlight from the planet being in the way, there were also dips in starlight observed just before and just after Uranus blocked the star: tell-tale signs of a ring system around the planet obstructing the starlight.
Images: Elliot and Nicholson
Uranus continues to play an intriguing role in models of solar system evolution.
It seems like something that belongs in a movie: An asteroid is headed towards Earth – can we deflect it by flying a big heavy spaceship into it to push it off course and save the planet?
NASA takes this question very seriously and is putting the theory to the test with the Double Asteroid Redirection Test (DART) mission launching on 24 November. Taking off on a SpaceX Falcon 9 rocket, it will speed towards the double asteroid Didymos. The mission is fairly simple: fly a 500kg projectile as fast as you can into Didymos’s tiny moon, Dimorphos, and see if it’s orbital velocity can be measurably altered.
To be clear, Didymos and Dimorphos are not on a collision course with Earth, we are safe for now. But astronomers estimate we have found only about 40% of all asteroids larger than 140m across, easily large enough size to destroy a city.
The logic behind this experiment is that if one day we do find an asteroid with Earth’s name on it we could send an impactor to alter the speed of the asteroid. It may only be by a fraction of a millimetre per second (mm/s), but over many years this tiny difference in speed can add up to a significant distance in space and so with enough warning we may cause the asteroid to miss the Earth. That’s the theory, now to put it to the test. Asteroids can be tricky to study, and their widely varying composition makes it difficult to extrapolate data from one study to the next.
Captain Kirk boldly went where quite a few people have gone before, with William Shatner hitching a ride to space on Blue Origin’s New Shepard rocket. Travelling to an altitude of 110km, this carries travellers well above the Karman line, the internationally agreed edge of space.
You might have noticed that the New Shepard rocket looks a little different to the sleek rockets we have become used to. To quote science communicator Scott Manley: “Rocket design is usually a team effort, which means if you want to churn out an ugly launch vehicle you have to actually assemble an entire team of aesthetically-challenged engineers and have them fight against the natural tendency for rockets to look cool.” So why such a design?
Image: Blue Origin
The reason is in the landing of the rocket and the safety of the people on board. Landing rockets is a difficult and dangerous task, so if you can make sure there are no people around when it happens, all the better.
The crew capsule at the top of the New Shepard is designed to detach and land separately under parachutes as the now uncrewed booster stage lands using its engine. The two separate at an altitude of about 100km so they have plenty of time to drift apart.
Here’s the important thing – the capsule needs to be less aerodynamic than the rest of the rocket so that it falls slower and doesn’t collide with the booster mid-descent. Hence why it has a wide base. The need to be aerodynamic going up and blunt coming down makes the top of the rocket look the way it does. Add in some internet culture and the rest is history.
NASA’s Lucy mission launched on an Atlas V rocket bound for the Trojan asteroids to explore the origins of the Solar System.
The Space Launch System launch vehicle for the Artemis 1 mission is finally fully assembled. This mission will carry an uncrewed Orion capsule to the Moon in February 2022 as a test flight for future human missions.
SpaceX conducted a static fire of Starship. Tests like these are vital for validating the hardware before attempting a launch and orbital flight.
A Russian film crew paid a short visit to the ISS to record footage for a movie.
Three Chinese astronauts were launched on a six month mission to the Tiangong Space Station.
It’s musical chairs on the ISS as the SpaceX Crew 3 mission will be launched and Crew 2 return home.
The Ariane 5 rocket successfully launched two communications satellites into geostationary transfer orbit. By itself a fairly standard launch for Arianespace, this mission is significant because it reaffirms the reliability of the Ariane 5 for its next lift off. Hopefully launching 18 December, it will be loaded with probably the most important payload it will ever carry, the James Webb Space Telescope.
Orion has nearly finished his long march across the sky, setting in the West just after sunset slightly earlier each day as …Explore
The two giants of the skies, Orion and Taurus, are getting low in the sky. So now is your time to see them before they depart …Explore
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