Caoimhín's Content

In this video we look a little further into the New Year, beyond New Year’s Day into January 2024 itself. Most things will remain pretty much the same, many parts of the sky change slowly even from month to month. Saturn is still visible in the evening, but very much only the early evening, along with shapes that dominated the sky a few months ago such as the Square of Pegasus. Jupiter remains with us for most of the night, along with the Pleiades and the constellation of Taurus. Constellations such as Orion, Gemini and Canis Major will be the centerpieces of the night sky, at least for the early part of the night. Of course, in January, by 9 o’clock it’s already been dark for a while.

Early January brings us the Quadrantid Meteor Shower. This is an interesting meteor shower for a couple of reasons. Firstly, at it’s peak, around the night of January 4th this year, it could produce a good number of meteors, comparable to the much more famous Perseids or Geminids , up to 100 meteors and hour some years. However this peak is very narrow, just a few hours, compared to peaking over several ours for most other showers. Secondly, its name. Most meteor showers are named after the constellation they originate in, and the radiant for this meteor shower is the constellation Boötes. However, constellations are human creations, and have only been finalized or officially defined in relatively recent history. Besides the huge variation across cultures, even in the 17th and 18th centuries astronomers were creating their own constellations or adapting older ones, and not all of those have survived. There was a constellation called Quadrans Muralis, the Mural Quadrant, a tool for measuring angles that was often used in ancient astronomy. The constellation is no more, but the meteor shower still bears its name. Lastly, the body that produces this meteor shower seems to be an asteroid now, but may once have been a comet. That is, it is an extinct comet, a ball of rock and dirt that has lost all its ice and liquid, shed as part of its tail, which it can now no longer produce.

Mercury is the interesting early morning object for January. Venus of course will stay with us for January as well, but the quick little planet closest to the Sun is just reappearing. After disappearing from the evening sky last year, Mercury has now come around the Sun and is starting to come back into view. It will reach its Greatest Western Elongation on the 11th. Mercury’s Greatest Western Elongation is when Mercury appears as far West of the Sun as it can. For this reason, we see it in the morning, above the rising Sun in the East. It might sound a little counterintuitive, but if Mercury is West of the Sun then we won’t be able to see it when the Sun sets in the West, as Mercury is further West than the Sun and so sets ahead of it in the evening. Either way, it will still be tricky to see. As we are still in winter time, the Sun is still pretty low during the day. This shallow angle of the ecliptic also effects how high we see the planets in the evening and morning, keeping Mercury close to the horizon. This is also true for Venus, but Mercury is even lower still, making it easily obscured by bushes, buildings or for on the horizon.

Around the 8th of January, the Moon passes quite close to the morning time planets. A narrow crescent Moon will sit in the constellation Scorpius, which is also just coming back into view in the morning, forming broad triangle with the two planets closest to the Sun. As the Moon follows a path close to the ecliptic, the Moon will always pass through, or at least close to, various famous constellations, and will often pass close to, or sometimes right over, the planets. When the Moon fully blocks out a star or a planet, it’s known as an occultation, where as a close or nearby pass is a conjunction. The Moon occults various things all the time, though occultations of bright stars and planets are the more interesting and rarer ones. Conjunctions are a bit more common and we do have a couple coming up in January.

Before we look at the conjunctions happening earlier in the night, and late in the month, there is another planet about to reappear in the morning sky: Mars. The Red Planet is already above the horizon while the Sun is still below it by late January, but the light of dawn will make Mars practically impossible to see. Under dark conditions, far from the city, and with the right equipment, you may be able to spot it, but Mars will rise into the morning sky and become more prominent as we push into February and March. Even with the glow of dawn, light pollution is still a factor, so only having to worry about one is a bonus and the light of the Sun won’t change much no matter where you go, where as light pollution will be much lower in the countryside. In this case, special equipment might mean more than just a telescope. Certain types of camera, such as a camera obscura or pinhole camera, let you see things that are far away without focusing light using lenses or mirrors, and usually without requiring you to look directly at the object you are observing. This can help keep your eyes safe when there is a lot of light coming into the sky.

As we move back to night time late inn the month, we can see that the path of the Moon takes it through some famous parts of the sky, right past the Pleiades and Jupiter. The Moon passes this part of the sky every month, and for much of the year it is visible when it does so, but only sometimes do we see something truly visually impressive. This month, on the 21st, the Moon gets pretty close to the Pleiades from our perspective here in Ireland, you can see the bright stars of the Pleiades just to the left of the Moon in telescopes or binoculars with a wide field of view. For other parts of the planet, as the Moon orbits around the Earth, it will appear to be practically on top of the Pleiades, but at the time that they’re high in our sky they won’t be quite as close. On the other hand, just a few nights earlier on 18th, the Half Moon will be right over Jupiter, a true close conjunction, the bright planet and the Moon will be right next to each other in the sky. This conjunction is perfectly placed for us here in Ireland, less so for people in other parts of the world. Just as the Moon and Pleiades move apart before we get a good look, so do Jupiter and the Moon before they rise for other parts of the planet.

Most things that we see in the sky, at least most of the things I normally deal with here, don’t vary much by your longitude. It won’t matter if you are in the Atlantic or the Pacific Mercury’s Greatest Elongation will be on the same date. Latitude often matters more, not only are we usually looking at the Northern Hemisphere, but even with the Northern Hemisphere, the times of sunset and sunrise can vary, as can the heights of planets above the horizon. In this case, for conjunctions, longitude really does matter, thanks to how fast the Moon moves relative to the planets and stars. Even just a few hours apart, different sides of the planet see slightly different phases of the Moon and the Moon will be in a slightly different positions. This helps give a little variation to our views around the planet.

To finish up the video we take a closer look at the Moon, but of course we’ve discussed the Moon many times here, so I’ll hold off rehashing my enthusiasm for the Half Moon and how it lets us see the lunar surface’s texture, I’m sure I’ll gush over it in future videos and articles at any rate. With so many interesting events coming up, particularly a slew of eclipses of various sorts, there’ll be plenty of reasons to look at the Moon in 2024, so I’ll hope you’ll come back and join me for them.