Astrophysicist

Tag: Jupiter

What’s in store for 2024

Happy New Year! I spoke with Glen Hunt on BBC Radio Lancashire this morning about what the Universe (and our exploration of it) might have in store for us this year. It certainly looks like it will be an exciting year for space exploration, and there are many potential discoveries that could be on the cards. Here are some things I’m particularly looking forward to.

The Sky in January

The first thing to look for is the planet Jupiter high in the sky for most of the night. Look towards the South if you are in the northern hemisphere, look to the North if you are south of the equator. Jupiter will be bright, and pretty unmistakable in the early evening.  Look with binoculars, if you have them, to see its moons (and cloud bands, if you’re lucky enough to have access to a telescope).

The ringed planet Saturn is also visible this month, but low in the South-West and fainter. Look with binoculars or a telescope for a view of the impressive ring system.  Saturn sets before 9pm and gets earlier as the month goes on, so catch it early if you can.  There is also a crescent moon close by on the 14th, with both objects low in the South-Western sky.

A sky map showing the locations of some highlights of the January sky.
The sky as seen from North-West England at 6.30pm on January 3rd. Jupiter is high in the South, Saturn is over to the South-West, and the winter favourite constellation of Orion is rising in the East. Image: Stellarium / the author.

If you’re up early, have a look for Venus (easy to spot) and Mercury (quite a lot more difficult!) low in the eastern sky before dawn.  Use binoculars for a better chance of spotting the elusive Mercury, BUT DON’T LOOK AT THE SUN with them!

One of the best meteor showers, but one of the least well-observed (thanks to the weather!), is the Quadrantid meteor shower peaking on January 4th. Unlike most meteor showers which originate from comet debris, this one is due to asteroid 2003 EH1 (possibly a dead comet, possibly a rock comet). This asteroid has an orbit around the Sun lasting 5.5 years, only taking it as far out as Saturn, unlike the majority of comets which spend most of their time beyond Pluto.   Although the body responsible was only discovered in 2003, the meteor shower has been known about since 1825. The radiant, the position the meteors appear to all come from on the sky, was in the now-defunct constellation of Quadrans Muralis (hence the name) – this location is now part of the constellation of Bootes the Herdsman today. 

The Quadrantids can be a very strong shower, with peak rates of more than 100 meteors per hour, but the peak is very short-lived and this year is hampered by daylight during predicted peak hours here in the UK. You have a better chance of seeing good activity from the Americas or Asia this year. Your best chance to view is in the early hours when the radiant is high, after 2am.  Sadly the Moon all rises just after midnight and is half illuminated, making viewing fainter meteors more difficult.  The short predicted peak of activity is between 0900 and 1500 GMT on January 4th.  

The sky looking East at 2.22am on January 4th 2024 showing the constellation Bootes, the location of the radiant for the Quadrantid meteor shower. Image: Stellarium / the author.

The sky later in the year

There will be the usual changing of the constellations as the seasons roll around. Orion is a winter favourite with lots of bright stars and a spectacular star forming region below Orion’s belt that is worth a look with binoculars or a telescope.

There are also a series of meteor showers that happen on the same dates each year as we pass through the debris left behind by comets or asteroids as they orbit the Sun. The ones to watch in 2024, aside from the Quadrantids in January, are the Perseids in mid-August and the Geminids in December. Other meteor showers will happen, but they are not predicted to be as active as these. For most details, keep an eye on the IMO’s Meteor Shower Calendar which is regularly updated.

And a couple of supermoons. While these are not particularly exciting from a scientific point of view, the full Moon is always impressive, and a full Moon at lunar perigee is bigger and brighter than usual, so will be worth a look if the skies are clear. Look up on September 18th and October 17th 2024. (And remember, the astronomical term for this is perigee-syzygy of the Earth-Moon-Sun system. Snappy!)

Spaceflight

2023 was an exciting year for spaceflight and solar system exploration missions, and 2024 is looking like it will be just as exciting. There’s certainly lots planned, both by space agencies like NASA and ESA, governments such as China, and the rapidly growing commercial sector.  Here are some things to look out for in 2024.

Europa Clipper is scheduled to launch in October, heading off to survey Jupiter’s moon Europa, an icy world that may support a sub-surface ocean.  There is a lot of interest in exploring the potential for habitability of Europa (you need liquid water, the right chemistry, and light/heat) and this probe will help with that by allowing scientists to determine the extent of any sub-surface liquid water and examine the geological processes at work.  It won’t arrive until 2030 though, but will complement ESA’s JUICE mission (launched in 2023) nicely when it does.

China plan to launch the next in their series of missions to the Moon with Chang’e 6 heading to the far side of the Moon to attempt the first sample return from the far side of the lunar surface (the side we never see from the Earth).  Likely launch in May.  We have lunar samples from the near side thanks to Apollo, but not from the far side, so comparing the two will tell us more about the history of the Moon.

June should see the maiden flight of the long-awaited Ariane 6, the European Space Agency’s replacement for the long-serving and highly successful Ariane 5 launch vehicle.  It will be able to carry a large payload to orbit, but could lose out commercially to SpaceX’s Starship once that starts flying successfully, and Blue Origin’s New Glenn heavy launcher expecting it’s maiden flight in August. Ariane rockets are expendable, whereas Starship and New Glenn are largely reusable which brings down the cost per launch substantially.

And of course the next Artemis mission taking humans around the Moon for the first time since the Apollo era, pencilled in for November 2024 (but, like all launches, this could slip).  Artemis 2 will be the first crewed flight of the Orion capsule, and see the first humans go beyond low Earth orbit since 1972, taking four astronauts around the Moon and back in what is likely to be a highly-watched mission.  Expect stunning photographs of the lunar surface!

As well as large programmes like Artemis, NASA have also commissioned a series of commercial companies to provide lunar landers for robotic and autonomous probes through the Commercial Lunar Payload Services (CLPS) programme.  The first of these missions, Peregrine 1, is due to launch on January 8th and will carry two rovers, several sensors, and a collection of time capsules. Several other launches are planned, expanding NASA’s existing work with outside commercial contractors that goes back decades.

We are also likely to see both another record year for satellites launched into low Earth orbit (making the risk of collisions ever more likely, and astronomy more challenging) and more new private operators beginning launch operations, including multiple commercial launches to the Moon, adding further competition to the market.

Biosignatures?

And finally (in Jodcast tradition), there is certainly a lot of interest in looking for evidence of biological processes in space, and it’s possible 2024 might be the year we first find solid evidence of biosignatures somewhere other than the Earth. This could be in samples from Mars, or it could come from further afield in the form of spectroscopic signatures from the atmospheres of exoplanets.

Since the 1990s we have discovered more than 5000 exoplanets around stars other than the Sun. The more we look, the more we find. Remember though that this is still challenging – we had the telescope for almost 400 years before we discovered the first solid evidence for extra-solar planets! And as is usually the case with new discoveries, we found the easier ones first.

Astronomers are using powerful telescopes with very sensitive spectrometers to split up the light coming from the exoplanets. This is challenging because a planet only reflects the light from its host star, rather than emitting its own light, so it is much fainter than the star and much harder to detect (which is why it took almost 400 years to find one!). But if you can do it, and split the light into its constituent colours to make a spectrum, you can then look for the signatures of chemicals in the planet’s atmosphere.

Some chemicals are associated with life, so those are the ones to look for. Many of these chemicals can also be produced by non-biological processes too, so finding a signature in the spectrum is only one part of the puzzle in many cases. But if we find one of them, it will certainly be tantalising.

There are also a lot of astronomers looking for signatures of life in the cosmos using a rather different method. Instead of looking for biosignatures, they are looking for technosignatures – evidence of advanced technology from signals that could not be produced in any natural way. This could be radio signals (like the radio and TV transmissions we have been sending into space for many decades now), or something more advanced such as a powerful beacon, or evidence of megastructures, or even evidence of some cataclysmic event.

It may sound like science fiction, but these are genuine research projects. The probability of finding either a bio- or technosignature may be low, but should we find evidence of life elsewhere in the cosmos, the implications really would be tremendous.

That’s not all folks

There are plenty more exciting events to look out for in 2024, from super moons to comets, results from previous missions, new images from JWST that will be as astonishing as ever, and many, many rocket launches. But it’s lunch time here, so I’ll leave it there for now. If you made it this far, thanks for reading! What are you looking forward to this year?

Planetary spectacular

You may have heard Prof Lucie Green talking about the planetary conjunction on BBC Radio 4’s Today programme this morning – there were five planets lined up neatly in the early-morning sky this morning! Don’t worry if you didn’t see it today, or it you tried and had cloudy skies, you can still catch it over the next few days.  Here’s where to look, and what to look for.

Mercury, Venus, Mars, Jupiter and Saturn all appear in a line in the early morning sky.

Planetary alignment of late June 2022 – visible view at 4.15am BST – as seen from NW England.

First thing is, you’ll need to be up early!  The view above shows the sky at 4.15am.  The Sun rises at 4.43am from where I am, so you won’t see much after that as the sky will be too bright to see anything other than the Moon!  If you can drag yourself out of bed at that time, here’s what you will see.

Looking East, with a good horizon (ideally up a hill, but anywhere that you can avoid tress, hills or houses to your East) you should be able to see in order going up from the horizon: Mercury, Venus, the Moon, Mars, Jupiter and Saturn.  That’s quite a view!  The Moon is only 14% illuminated, so will appear as a nice crescent shape.  At magnitude -3.9, Venus will be the brightest of the set, less than 10 degrees above the horizon at 4.15am.  Mercury is the trickiest to spot, but will be between Venus and the glow of the pre-dawn Sun.  At magnitude -0.3, it will be a challenge to spot in the skyglow as by this time it is still only four degrees above the horizon.  If you have binoculars you will find it easier to catch, but be very careful NOT TO LOOK AT THE SUN!  Moving a little round towards the South, Mars is next.  At magnitude +0.5 it will still be easy to spot – you’re looking for something with a reddish/orange colour to it.  Moving up and further South again, you will find the next brightest of the set, Jupiter.  With a magnitude of -2.4, this planet is always hard to miss in the night sky.  If you have binoculars, have a look and see if you can spot the four largest Moons of Jupiter: Io, Europa, Ganymede and Callisto.  Further round, almost due South at this time, you will find the last of the set: Saturn.  At magnitude +0.6, Saturn is a little fainter than Mars, but yellow rather than red in colour.  If you have your binoculars handy, have a close look and see if you can spot the rings.  If you have good optics and a steady hand, you might just see them!

[Aside: If you look carefully, you will also note that Uranus makes an appearance in the lineup.  You are unlikely to spot this without a telescope though, as it has a magnitude of +6.  In good conditions and with good eyesight, you might spot this with the naked eye during darkness, but not in the early hours with the Sun brightening the sky.  Not far from Venus is the Pleiades cluster of stars – now that is worth a look with the binoculars as it’s always an impressive sight.]

Why are the planets in a line?” I hear you ask.  That’s a good question, and it comes down to perspective.  The planets are actually always in a line, it’s just that it only becomes obvious when you have a close alignment such as this.  The reason for this is because all of the planets orbit the Sun is a very similar plane – you can imagine the solar system sitting on a dinner plate with the Sun at the centre and all the planets moving in (almost) circular orbits around the surface of the plate.  If you imagine yourself as an ant sitting on the dinner plate, you would see the planets sitting on a circle around you.  How does this look to us?  Here’s the same view as above, but now with this plane drawn on:

The planets all lie close to the plane of the ecliptic on the sky.

Planetary alignment of late June 2022 – visible view but with the plane of the ecliptic added.

This plane is actually the projection of the path of the Sun around the sky as seen from Earth.  We’re orbiting the Sun of course, not the other way around, but from our perspective we see the Sun move across the sky relative to the background stars over one calendar year.  The path the Sun takes across the sky is called the ecliptic by astronomers.  We do like our jargon.

The orbits of the planets in the Solar System lie close to the ecliptic line, which is the apparent path of the Sun as seen from Earth projected out into the sky.

Planetary alignment of late June 2022 – visible view but with the ecliptic and orbits of the planets added.

The above view is the same, but now I’ve added the paths of the planets as well.  You can see that, as the planets orbit the Sun, their orbits never take them very far from the ecliptic.  That’s because of that dinner plate effect I talked about earlier.  The planets are all moving about close to the plane of the solar system, and so are we, so they appear to closely follow the path of the Sun on the sky.  It’s not exact because the planets all have slightly non-circular orbits, and their orbits are all very slightly tilted compared to that of the Earth, but the planets are essentially always in a rough line from our perspective.  Pretty cool, huh?

Finally, if you’re finding it annoying that the Sun makes Mercury so hard to spot, you’re not alone.  Many astronomers have rarely caught a glimpse of it!  Since Mercury never moves very far from the Sun, and it’s quite small and rocky so doesn’t reflect a lot of light, it can be challenging to observe.  The best solution to this problem?  Visit the Moon where you don’t have an atmosphere to contend with!  If you viewed the sky at the same date and time from the (far side) of the Moon, here’s what you would see:

With no atmosphere, the sky does not appear bright blue as it does on Earth, hiding the stars during the day. Instead, the stars are visible all the time, whether the Sun is in the sky or not.

The same planetary alignment, but viewed from the Moon where there is no atmosphere to hide Mercury!

This is the view at the same date and time, but from a location of 25°43’N 157°19’E on the Moon’s surface.  The Sun is in the sky, but because the Moon has no atmosphere to speak of, there is no scattering of the Sun’s light, and the sky does not appear bright blue.  Instead, all the stars are still visible, just as if it were night time.  The Earth is below the horizon from here, so it’s not in the sky right now from this location.

As visiting the Moon is (sadly) not an option for most of us any time soon, my advice is to choose a nice hill, pack yourself some sandwiches and a flask of your favourite beverage, and go for an early morning hike.  Or camp up there with an alarm clock.  Good luck!

All images made with Stellarium.

© 2024 Dr Megan Argo BEM

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