Ever seen Uranus? No, be serious, have you ever seen the planet Uranus? April 2024 is a good time to look for it, because it’s right next to Jupiter, the brightest planet in the sky at the moment. And on 10 April there’s a spectacular line-up of Jupiter, Uranus, a thin crescent Moon and even a comet, all close together in the sky.
Jupiter is the very bright object over to the west in the early evening at the moment. You need to look for it as soon as the sky gets dark, as it is getting quite low now and will be too low for good observation after about 9:30 pm.
It so happens that right now it’s very close to the ice giant Uranus. This isn’t easy to spot, and you’ll definitely need binoculars to see it, but being almost in line with Jupiter makes it much easier to find.
Jupiter is much closer than Uranus, and it moves much faster in its orbit around the Sun. So during April Jupiter is moving from west to east through the sky, but it is sinking slowly in the twilight at the same time, so it gets lower and lower each evening. Take a look at it whenever you can but really hope for a clear sky on the evening of 10 April because there’s a very special line-up as shown in this view:
Not only is Jupiter close to Uranus, but the lovely crescent Moon is there as well. And to the lower left, marked as 12P/Pons–Brooks, is a comet! More about this below.
The closest that Jupiter gets to Uranus is on 20 April, when the two planets are only half a degree apart – that’s the diameter of the Moon as seen on the sky. On that occasion, Jupiter is 888 million km away from us, and Uranus is over three billion km away – 3.45 times farther away than Jupiter. But by this time Jupiter is lower in the sky and well into the twilight, so you might have more trouble finding it. The comet is 240 million km away and the Moon is a mere 367,000 km away on 10 April.
So what’s all this about a comet?
It’s true, there is a comet in the sky at the start of the month. It’s called Comet Pons–Brooks, after two 19th-century astronomers and its catalogue number is 12P, indicating that is it a periodic comet, one that orbits the Sun in a period of less than 200 years. Its actual period is 71 years. You’ve probably heard of another very famous periodic comet, 1P/Halley, which comes around every 76 years. There’s no actual link between Halley’s Comet and this one – in fact, Halley’s Comet is at its most distant point from the Sun around now and won’t be back until 2061.
Pons-Brooks isn’t as large a comet as Halley, however, but we don’t see comets all that often, so make the most of this one. Forget the idea that a comet whooshes through the sky like a skyrocket – although it is actually whooshing, it’s so far away that it only moves slowly from night to night. You might be able to see it with binoculars, but because it’s in the twilight sky you probably won’t see much of a tail. Although it is fairly bright as comets go, it won’t stand out very clearly – look for a faint fuzzy spot. Here’s a map of its track through the April sky:
