January 2025
The Sky Tonight - January 2025
January continues the season of Birak, and the hot weather isn’t going anywhere anytime soon. The night sky presents a parade …
ExploreNew Moon
March 3
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The casual observer
The outer sections of the Milky Way are still bright overhead, with many identifiable star patterns to hold your attention. Orion and Taurus are now in the north-west in the evenings, as the summer finally draws to a close. Leo the Lion can now be seen making its way up in the north-eastern sky in the early evenings followed by Virgo inching its way above the horizon as the month goes on.
The Moon makes its monthly perambulation across the night sky, passing extremely close to Uranus on 7 March. It will actually pass in front of Uranus as seen from Perth – called an occultation – on 25 June, so hold out for that one.
The remaining visible planets are putting on an impressive morning display all month, glowing bright in the eastern sky before dawn, and are joined by the waning gibbous Moon at the beginning and end of the month.
The Gamma Normids meteor shower runs from about 7 March to 20 March, peaking around 15 March. This is not a particularly spectacular shower so you can expect to see maybe six meteors per hour under good conditions, though the Moon is in about the worst possible phase during this shower’s run which may inhibit your viewing.
Most of what is known about this meteor shower comes from observations made in Western Australia. The original body of these meteors is unknown, but their orbits can be worked backwards to determine that the parent body was definitely a short-period comet well inside the Solar System (although the orbits are too uncertain to conclude more than that).
As this hot summer draws to a close, suddenly it is the Autumn equinox on 20 March. This is the point on the Earth’s orbit where the Sun passes directly over the equator. Observers on the equator, having seen the Sun slightly to the south for the last six months, will observe it passing directly overhead, and then for the next six months will see the sun move into the northern part of the sky.
This also means that there will be exactly 12 hours of day and 12 hours of night everywhere on Earth on this date. That’s what Equinox means, after all: Equi – Equal, Nox – Night. Seen from space, Earth’s rotational axis lies in the plane of the terminator on this day.
Image: Earth as seen by Meteosat-9
Credit: NASA Earth Observatory EUMETSAT
Dates of interest
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Chang’e 5-T1 booster impacts the Moon.
March 4
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Moon near Uranus.
March 7
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Moon close to Pleiades.
March 8
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Mercury, Venus, Mars and Saturn inside Capricornus.
March 8
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Gamma Normids peak.
March 15
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March Equinox.
March 20
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Venus, Mars, Saturn, Jupiter and Moon visible in Eastern sky before sunrise.
March 31
Planets to look for
The planets are definitely favouring the morning people this month, as all the easily visible planets are showing in the eastern sky just before sunrise.
On 8 March, Mercury, Venus, Mars and Saturn are all located inside the constellation of Capricornus for one day only. You’ll have to be up in the wee hours before sunrise to catch it. Mercury is moving rapidly eastward at this stage, so will be outside the boundary by tomorrow.
Where Mercury departs, the Moon fills this absence later in the month, and you’ll be able to catch Venus, Mars, Saturn and the Moon inside Capricornus on 28 and 29 March.
Jupiter is in conjunction with the Sun on 5 March, meaning it’s literally on the opposite side of the sun form the Earth. The word conjunction implies that they are at coinciding points in the sky as seen from Earth. If you want to look at Jupiter, you have to look at the Sun. Not recommended!
Later in the month however, Jupiter makes a brief appearance in the minutes before sunrise, very low on the eastern horizon. It will be joined by the waning crescent Moon on 31 March at about 5.30am.
Constellation of the month
Taurus, the Bull
Taurus is a large constellation in the northern sky, notable for it’s distinctive V-shaped pattern of stars that form the horns of the bull, and the red giant star Aldebaran forming it’s eye. The two stars Tianguan (Zeta Tauri) and Elnath (Beta Tauri) allow the horns to be extended far to the east.
Taurus is located pretty much exactly opposite the centre of the Milky Way, meaning when you are looking at Taurus, the centre of the galaxy is exactly behind you. The constellation is also notable for the two open clusters, the Pleiades and the Hyades, with most of the stars making the face of the bull being part of the Hyades. Recognition of the Pleiades as the ‘Seven Sisters’ is shared by many cultures across the world.
Taurus is one of the most ancient constellations, with studies even identifying it in cave paintings dating back 17,000 years as showing the bull and the Seven Sisters together in the sky.
Being so recognisable, there are myriad stories associated with this pattern of stars. Ancient Egyptian stories had the bull being a sacrifice before the new life of spring. Babylonian stories have the goddess Ishtar sending the bull to kill Gilgamesh for rejecting her advances, while Greek stories have Zeus disguising himself as the bull in order to abduct the princess, Europa.
Object for the small telescope
A stellar lifecycle in a single constellation
Being so ancient and full of stories, Taurus is appropriately equally filled with wonderful things to point a telescope at. With a little navigation, you will be able to see the entire life cycle of a star taking place inside the borders of this constellation.
Start at the Pleiades. What looks like half a dozen stars with the naked eye is easily revealed to be hundreds more with even a modest telescope. Star formation occurs when large clouds of gas collapse under their own weight, eventually fragmenting into individual stars. Newly formed stars eventually burn away the remaining gas, and all of this is on display in the Pleiades.
Image: The Pleiades. Credit: NASA, ESA and AURA/Caltech
Swing east to the Hyades. After a period of star formation, clusters like the Pleiades ‘evaporate’, with individual star systems being ejected from the group like molecules evaporating from a drop of water. As the cluster evaporates, we see a very open cluster of stars, just like the Hyades.
Images: The Hyades. Credit: Mura, CC BY-SA 3.0
Once they’ve escaped from the cluster, stars then go about their ‘daily’ lives until they begin to run out of fuel, at which time they begin fusing material in layers outside of the core, causing the star to expand and turn red, as seen in Aldebaran.
Aldebaran is a red giant star, slightly heavier than the Sun and hundreds of times brighter. Though it is in the same part of the sky, it is unrelated to the Hyades, it just happens to be in the same direction. It is near the end of its life and will eventually expel its outer layers and disappear into the night.
Heavier stars, however, end their lives with almost inconceivable violence, undergoing a core collapse supernova. This is exactly what happened in 1054, when a star in Taurus, not far from Tianguan, exploded so brightly that it could be seen during the day for several weeks.
Centuries later, modern telescopes pointed at the location discovered the Crab Nebula.
Image: The Crab Nebula. Credit: Astrobackyard
The expanding cloud from the explosion surrounds the rapidly spinning pulsar at its centre. Pulsars are the extremely dense collapsed cores of massive stars and are basically the last stage in the life cycle of high mass stars.
As for why it’s called the Crab Nebula, it’s because of the original drawing made by the first astronomer to observe it.
Image: First drawing of Crab Nebula, alongside modern image. Credit: The Messier Catalog.
Images of the Crab Nebula taken years apart show the expansion of the supernova remnant, as well as shock waves kicked up by the rapidly spinning pulsar, as seen here in this jaw dropping video: Crab Nebula Timelapse: “Epochs” (1999-2021)
And about that rocket …
You have probably heard about the rocket that will crash into the Moon soon. At 8.25.58 pm AWST on 4 March the Moon will get a new crater as the several tonne spent rocket impacts at 2.58km/s. The rocket was originally mis-identified as the second stage of a SpaceX Falcon 9, but is now thought to be the third stage from a Chinese Long March 3C rocket that launched the Chang’e 5-T1 mission. While interesting by itself, at a deeper level this is a fascinating story about the self-correcting nature of science.
Everything is based on predictions by Bill Gray, an expert in calculating trajectories of orbiting bodies. On 11 Feb 2015 SpaceX launched NASA’s DSCOVR satellite. Shortly after launch, astronomers noticed a new piece of space junk appear. Aware of the launch and expecting to find a new piece of junk show up, Gray identified it as the SpaceX rocket. Fast forward a few years and Gray noticed that the object was due to impact the Moon, which got a lot of media attention.
Video: The rocket (red trail) has two close encounters with the Moon (green trail) before colliding on 4 March. Time interval between dots is one hour. Credit: Smith, Scitech.
However, a NASA scientist working on the DSCOVR mission pointed out that the junk was moving too strangely to have come from the DSCOVR rocket. After checking records from other launches around the same time, Gray determined that its orbit matched that of the Chinese rocket launch.
Simultaneously, scientists from the University of Arizona used reflectance spectroscopy to study the piece of junk and determined that the reflection spectrum of the junk did not match the type of paint used on SpaceX rockets. Instead, it matched the paint used in Chinese rockets.
At the same time, another orbital debris expert noted that the orbit of the junk was very similar to the 4M satellite launched on the same Chinese rocket. Taken altogether the evidence is quite conclusive that it is the Chinese booster and not SpaceX’s after all.
Rockets crashing into the Moon is not that new. During the Apollo missions, astronauts left seismometers on the Moon to measure quakes and then subsequent Apollo missions would deliberately impact the upper stages of the Saturn V rocket into the Moon to cause a quake with a known amount of energy to calibrate the seismometers. More recently, the LCROSS mission booster was impacted into the Moon to kick up a cloud of dust for the satellite to study for signs of water.
Image: Apollo 16’s S-IVB booster impact site captured by the Lunar Reconnaissance Orbiter (LRO). Fittingly, the LRO’s booster also crashed into the moon as part of the LCROSS mission. Credit: NASA
If you’re upset by space junk in High Earth Orbit polluting the Moon, consider Gray’s comments: “Without exceptions that I know of, nobody has cared much about where high-altitude junk goes, to the point where I’m the only person keeping track of it, almost entirely in my spare time … Basically, this could have happened with various objects launched by various countries … high-flying space junk has not been a concern for anybody; it’s not just SpaceX (sic, China).” Perhaps this may be a catalyst for greater responsibility with deep space missions. To be clear, Low Earth Orbit junk is monitored closely.
For what it’s worth, Chang’e 5-T1 was a successful pathfinder for the Chang’e 5 mission – be careful not to confuse them! Chang’e 5 launched in 2020 and landed on the moon to collect rock samples before returning to Earth.
Unfortunately, we won’t see the booster impact. It’s on the far side of the Moon. Also, it’s on 4 March, just after New Moon, meaning the Moon will be close to the Sun in the sky making observations from Earth impossible.
Ironically, or appropriately, DSCOVR is perfectly positioned to see the impact, however unlikely.
Video: DSCOVR views the Moon transiting the Earth. Credit: NASA.
Other space news
See some spectacular footage of the stage separation of a SpaceX Falcon 9
Why are comet heads green? Now we know.
Landast 9 is now operational and returning observations.
Just how do you align the mirrors of the James Webb Space Telescope?
A white dwarf has been spotted consuming an Earth-like planet.
A detailed breakdown of all 55 engines on the Space Launch System? Yes please.
