March 2024
The Sky Tonight - March 2024
April brings us into the season of Djeran, characterised by arrival of some much-needed cooler nights. The eastern sky is the …
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February 3
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The casual observer
February brings us to Bunuru – the second summer. If you can believe it, the last two months of appallingly warm weather were only the first summer. Expect more hot and dry days. The night sky compensates for this by putting on a great show for constellation hunting.
You can see a distinct band of bright and easily recognised constellations stretching from the southeast – marked by the Southern Cross and Centaurus – over to the northwestern group – Orion, Canis Major, Canis Minor and Taurus low in the northwest. Bridging the sky is the great Argo Navis, made up of Carina, Puppis and Vela. Use an app like Stellarium or Sky Safari if you are unfamiliar with any of these constellations.
Image: Many bright and famous constellations on display during February.
Credit: Stellarium
Easily recognisable constellations bring with them a fun little side quest – easily recognisable satellites. Here’s the technique: Step 1: Go out in the early evening (important!, not late evening) and find yourself an easily recognisable patch of the sky.
Image: Orion and Taurus. Hard to miss these two.
Credit: Stellarium
Step 2. Wait, and the satellites will come to you. That’s all there is to it. Because Orion, for example, is such a distinct pattern of stars, it is very obvious when a bright object in that part of the sky is out of place. There are more than eight thousand satellites in Low Earth Orbit as of this writing, so on a good night you won’t have to wait more than a few minutes staring at the same part of the sky before a satellite passes through it.
Image: That wasn’t there a minute ago!
Credit: Stellarium
Satellites move across the sky at a steady rate, and they don’t blink or flash. If it flashes, it’s probably an aeroplane. With practice you will easily be able to tell the difference.
The Alpha Centaurids meteor shower peaks around Feb 9. These meteors appear to emanate from the region of the sky near Alpha Centauri and travel fast. It is not the most prolific shower in the world, but you might see a few meteors per hour coming from this direction as you go about your stargazing.
For the early risers, the first week of the month presents you with a good view in the eastern sky before sunrise as Venus, Mars and Mercury all appear close together. The best day to look is Feb 8 when the trio are also joined by the Waning Crescent Moon.
Image: Four rocky celestial bodies in the eastern sky on Feb 8.
Credit: Stellarium
The New Moon this month occurs when the Moon is at perigee, its closest distance to Earth in its orbit, making it appear larger in the sky. For this reason, it is called a ‘Super New Moon’, but its low illumination may make this hard to notice. Strange that you never hear crackpots claiming Super New Moons cause earthquakes or anything else, despite happening just as often as the Super Full Moons they claim do.
Speaking of Full Moons, about two weeks later the Moon will be around the other side of its orbit and fully illuminated. This means it is at its most distant point form Earth, looking smallest in the sky, while it is at Full Moon. This is called a Micro Full Moon.
Jumping for Joy
This year is a leap year, so February has 29 days this year. Why do we have leap years? It’s because Earth takes slightly longer than 365 days to orbit around the Sun. About 6 hours, in fact, or ¼ day. Every 4 years, these ¼ fractions of a day add up to a whole day. Earth is now exactly one day behind in its orbit compared to the calendar.
Image: Earth takes slightly longer than 365 days to orbit the Sun. Note: Orbits offset for clarity only. Not to scale.
Credit: scienceabc
If we ignored this missing day and didn’t have leap years, the calendar would lose time with the location of the Sun by about 1 day every 4 years. At first this may not make a huge difference, but after a century the calendar would be out of sync with the Sun by about a month.
Remember that time you tried growing tomatoes in July hoping to get lucky, and instead they all died? Different crops can only be planted at specific times of year, determined by the Sun. We need to adjust the calendar to match the Sun, not hope that things will just work the other way round, so we chuck an extra day into February every four years to balance the calendar. Think about that next time you sit down to a delicious plate of in-season Brussels sprouts.
ISS sightings from Perth
The International Space Station passes overhead multiple times a day. Most of these passes are too faint to see but a couple of notable sightings* are:
| Date, time | Appears | Max Height | Disappears | Magnitude | Duration |
| 8 Feb 8:52 PM | 10° above NW | 83° | 72° above SSE | -3.8 | 3.5 min |
| 9 Feb 5:02 AM | 10° above SW | 57° | 10° above NNE | -3.7 | 6.5 min |
Table: Times and dates to spot the ISS from Perth
Source: Heavens above, Spot the Station
*Note: These predictions are only accurate a few days in advance. Check the sources linked for more precise predictions on the day of your observations.
Dates of interest
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Fringe WORLD show ‘Dome Date Night’ in the Scitech Planetarium (Link at the bottom of the page)
February 2
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Fringe WORLD show ‘Dome Date Night’ in the Scitech Planetarium (Link at the bottom of the page)
February 3
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Venus, Mars, Mercury and the Moon in the eastern sky before sunrise
February 8
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Fringe WORLD show ‘Dome Date Night’ in the Scitech Planetarium (Link at the bottom of the page)
February 9
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Fringe WORLD show ‘Dome Date Night’ in the Scitech Planetarium (Link at the bottom of the page)
February 10
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Close approach of Venus and Mars
February 22
Planets to look for
Jupiter continues to dominate the northwest sky in the evenings, shining brightly at about magnitude –2. The same can’t be said for Saturn shining at magnitude 2 as it chases the Sun over the horizon shortly after sunset. It is about to pass behind the Sun as seen from Earth, so is largely unobservable after the first few days of February.
Venus is still visible in the morning sky before sunrise. It is getting lower in the eastern sky as the month progresses, while Mars has reappeared from behind the Sun and is getting higher. From Feb 17 – 27 you can watch the two planets have an apparent close approach in the sky, closing in to a separation of about 2/3 or a degree on Feb 22.
Mercury is visible in east for about the first 2 weeks of February before getting lost in glare of Sun again. It is visible as the smallish object below the red Mars, which is itself below the bright Venus.
Constellation of the month
Pyxis
Quick! Quess what this stick figure represents:
Image: A stick
Credit: Stellarium
Did you guess a stick. Or a small dog? This constellation is in fact represented as a mariner’s compass.
Image: Pyxis’s artistic representation
Credit: Stellarium
Pyxis is a small constellation in the southern sky, often associated with the Argo Navis, described above.
The brightest star in the constellation, Alpha Pyxis, comes in at only magnitude 3.68. It is actually several thousand times brighter than the Sun, but at a distance of 880 light years that brightness is diminished.
Pyxis is home to the interesting star system T-Pyxidis, a binary system consisting of a white dwarf and a low-mass Sun-like star. The white dwarf draws matter onto its surface off the less massive companion star. Every couple of decades enough material has accumulated to ignite a brief but furious period of fusion and the star system increases in brightness from a miniscule magnitude of 15.5 up to around 7. Such an event is called a nova, and T Pyxis is referred to as a recurrent nova, with six recorded events since 1890.
Image: Gaseous blobs of debris surround the white dwarf of T Pyxis, while the low mass companion is visible bottom centre.
Over time, nova events add mass to the white dwarf star and eventually it becomes so massive it exceeds the Chandrasekhar limit – the maximum mass that a white dwarf star can support – and the whole star collapses and explodes as a Type 1a supernova. T Pyxis is expected to go supernova sometime in the next 10 million years.
Object for the small telescope
Close encounters of the world kind.
Be sure to take a look at the close encounter of Mars and Venus on the morning of Feb 22. You’ll need to be out before sunrise, and the proximity of the event to the eastern horizon may hamper things slightly.
Image: Venus and Mars above the eastern horizon, 5am Feb 22
Credit: Stellarium
Interestingly, both planets are roughly on the other side of the Sun from Earth, meaning they present almost fully illuminated faces in our direction. For the close, large and reflective Venus this is a boon, and the planet shines at magnitude –3.4. For the smaller, less reflective Mars the effect is diminished by the much greater distance, and it shines at a mere 1.8 magnitude, making Venus about 110 times brighter during this encounter.
Of course, it is also worth pointing out that despite their apparent closeness in the sky, they will still be separated by about 115 million km in real life on this date.
Goodbye to Ingenuity
NASA’s Ingenuity Mars Helicopter has involuntarily concluded its mission flying around on the red planet. Ingenuity arrived on Mars in February 2021 along with the Perseverance Rover. It was intended to be a technology demonstration, with a target of 5 flights over 30 days.
Image: Ingenuity on Mars, as photographed by the Perseverance Rover
Credit: NASA
During its 72nd flight on Mars on Jan 18, communication was lost as the helicopter attempted to land. Ingenuity’s 71st flight on Jan 6 ended with the helicopter making an unplanned emergency landing, so flight 72 was a quick ‘pop up and look around’ mission to try to determine the helicopters’ location after the emergency landing.
Shortly before the end of the flight, the Perseverance Rover lost contact with Ingenuity briefly. Once communication was reestablished, transmitted imagery revealed the rotors had sustained damage during the landing of the craft.
Image: Shadow of Ingenuity’s rotor reveals the end of the blade is missing. The craft will not fly again.
Credit: NASA
The end of the mission, while unfortunate, concludes an overwhelmingly successful mission. Ingenuity is the first machine to achieve controlled flight on another planet. Lasting almost 3 years, Ingenuity far exceeded its planned lifetime, a habit of Mars exploration vehicles.
Video: Ingenuity as videoed by Perseverance. Still flying high in our hearts.
Credit: NASA
Ingenuity’s legacy will be in its demonstration that areal robotic missions are achievable. Future Mars missions will certainly explore fleets of robotic flying vehicles. The mission will also bolster the confidence in the Dragonfly mission.
Dragonfly is a NASA mission currently under development with the intention of launching a landable quadcopter to Saturn’s largest moon Titan to search for signs of prebiotic chemistry.
Image: Artist impression of Dragonfly on Titan
Credit: NASA/APL
From exploring a dried riverbed on a small red planet to exploring seas of liquid methane on Titan, areal spacecraft have an important role to play in solar system exploration.
Meanwhile in the Scitech planetarium
Dome Date Night. Get your tickets here
