Author: Megan (Page 1 of 2)

More asteroid near misses – and one hit!

The early hours of January 27th 2023 saw the closest approach to Earth of asteroid 2023 BU.  The fact that this particular space rock was only discovered on January 21st, just a week earlier, combined with it passing just 3,600 km from the surface of the Earth (0.03x the distance between the Earth and the Moon) got the media rather excited.  It’s trajectory brought it closer to the Earth than orbit of our geostationary satellites, but still well above the 200-300 km of things like the International Space Station located in low Earth orbit.  Given how far apart geostationary satellites are, our communications infrastructure was not in any significant danger (this time).

This particular asteroid was estimated to have a diameter of 4-8 metres and was travelling at a speed of around 9.3 kilometres per second as it passed by.  This might sound big, but it’s tiny by asteroid standards.  If it had hit the atmosphere, it would have most likely burnt up entirely, leaving only tiny fragments reaching the ground, if at all.  For comparison, the rock that disintegrated over Chelyabinsk in 2013 was estimated to be 20 metres in diameter – that one exploded in the atmosphere, showering small chunks of debris over the town.  Assuming a similar density to the Chelyabinsk rock, asteroid 2023 BU likely had a mass of less than 1,000 tonnes.

The asteroid moves rapidly past the Earth at closest approach before moving away again and slowing down.

Animation showing the close approach of asteroid 2023 BU on January 27th 2023. Image credit: ESA.

The thing is with an asteroid passing this close to a much larger object, the encounter will change its future orbital trajectory.  Prior to this encounter, observations show that this asteroid orbited the Sun every 359 days.  Observations made after the encounter allowed experts to model its new orbit, finding that it now orbits the Sun every 425 days.  It won’t be back at the Earth now until December 24th 2029 when it will be some 14 million km at closest approach.  Nothing to worry about.  In fact, they’ve modelled its position all the way to 2139.  The closest it will pass to us in that time is 528 thousand km in January 26th 2066.

The thing is, this happens all the time.  As of today, according to the IAU’s Minor Planet Center, there are 31,207 known near-Earth asteroids, 850 of which are larger than 1 kilometre in size, and 2,328 potentially hazardous asteroids.  And we’re finding new ones all the time.  Just this year (we’re still only in February) we’ve had at least eleven objects pass closer than the Moon, at least five of which were not discovered until after closest approach!  Again, don’t panic, they’re all pretty small and would be highly unlikely to do any damage.

2023 CX1 entering the atmosphere.  By Wokege.

2023 CX1 entering the atmosphere on Feb 13th 2023. By Wokege.

One of these actually impacted the atmosphere.  Asteroid 2023 CX1 was discovered less than seven hours before impact!  Again, don’t panic, it was tiny, about 1 metre in diameter, and burned up as an impressive fireball somewhere over the English Channel / Northern France (above).  You can see reports of sightings on the IMO fireball report catalogue.  This was only the seventh impacting asteroid to be discovered before it actually hit the atmosphere.  It’s still pretty difficult to find these things in advance.

If you want to look at the population characteristics, JPL’s Center for Near Earth Object Studies has some data and charts you can play with – I’ve included a couple below showing the discovery rate of NEOs, colour-coded by survey, and the size distribution.

Bar chart showing the increase in discoveries in recent years.

Discovery rate of NEOs, colour-coded by survey, dated Jan 31st 2023. Credit: CNEOS.

The above plot shows the increase in discovery of near-Earth objects.  The surveys that have discovered the most objects are the Catalina Sky Survey and Pan-STARRS, although many are still discovered by amateur astronomers – including 2023 BU and 2023CX1!  This is one of the science goals of the Vera C. Rubin telescope‘s Legacy Survey of Space and Time (LSST), to make an inventory of the solar system.

There are far more small NEOs known than large ones.

Size distribution of NEOs discovered to date, dated Jan 31st 2023. Credit: CNEOS

This one shows the size distribution of NEOs discovered so far.  As you can see, there are not many in the 1000+ metres category – luckily!  Those are the ones most likely to cause us damage, but they are also the easiest to spot.  The thing with space rocks is that they are rocks.  Rocks are usually pretty dull looking, they are often dark colours and don’t reflect much light.  That is a problem when your trying to find them with an optical telescope – they don’t reflect much light, so are pretty faint and therefore difficult to detect.

If you’re a keen astronomical observer and are looking for a project, here’s the Minor Planet Center’s list of NEOs needing confirmation.  More observations are always welcome, helping to pin down asteroid orbits, and you don’t need sophisticated equipment to contribute.

Keep watching the skies – there will be more of these!  But they will get harder to spot as we launch more and more satellites, and install more and more lights.


Space Juice

It’s been a busy week or so for news stories about the solar system!  Last Friday was the list time we would get to see Juice, Jupiter Icy Moons Explorer, before it was shipped off to Kourou in French Guiana for launch on an Ariane 5 rocket in April.  Juice is heading off to the Jupiter system to explore the planet, its magnetic fields, and some of its largest moons: Europa, Ganymede and Callisto.  This mission has been in development for years, having been selected in 2012 as the first “large-class” mission in ESA’s Cosmic Vision 2015-2025 programme, and has contributions from both NASA and the Israeli Space Agency.

Jupiter Icy Moons Explorer

As BBC local radio stations amusingly described it last Friday, Space Juice will achieve several firsts.  It will be the first spacecraft to orbit a moon in the outer solar system – we’ve orbited our own Moon, but never the moon of another world.  It will also be the first flyby of the Earth-Moon system (called a lunar-earth gravity assist), which is a flyby of the Moon first and then another flyby of the Earth just 1.5 days later – by doing this manoeuvre, Juice will save a significant amount of propellant.

Flybys are always important for getting to the outer solar system, they can save you a lot of propellant which gives you more mass to use for funky, exciting science instruments!  In this case, although Jupiter is only about 600 million km from Earth, there is no rocket powerful enough to go directly there.  By making flybys of Earth (August 2024), Venus (August 2025), and Earth again (September 2026, January 2029), Juice will travel more like 6.6 billion kilometres!  It’s worth it though, for the extra science payload.

What’s it going to do?  Juice will give us the most detailed view of Jupiter and its icy/water world moons (Ganymede, Callisto and Europa).  Jupiter is the archetype gas giant planet.  We keep finding Jupiter-like planets around other stars, but they are very difficult to study due to their distance – it’s very hard to image them.  Jupiter is much easier to study, and learning more about this solar system giant can help us understand those Jupiter-like exoplanets in more detail.  All three moons thought to have subsurface oceans of liquid water, so are important places to go searching for evidence of life.

Exploring moons

Jupiter and its moons are like a mini solar system.  Jupiter sits in the middle of a dancing melee of smaller rocky objects in (almost) circular orbits around it.  Why will Juice visit these three moons in particular?  Well, we think they all have some liquid water below the surface.  And they are all quite different, so comparing them will be really interesting.

Europa has an obvious icy crust, so the surface features are actively changing.  Imagine watching the ice creak and move slowly in Antarctica – but on a planetary scale!  Juice will make a couple of flybys of Europa to search for biosignatures, to see how much water there might be under the surface, and explore the moon’s geology and activity.  Europa is very close to Jupiter, it’s a very harsh environment so Juice will only make two flybys of this moon.

Ganymede is older and has a less active crust.  It has an older surface which is rocky, rather than icy, and gives us a window on a geological record that spans billions of years of solar system history.  It’s also the only known moon with a magnetic field, implying that it has a molten core like the Earth.  Juice will explore Ganymede’s magnetic field, look for subsurface pockets of water or evidence of a sub-surface ocean, measure its complex core, its interaction with Jupiter, and help us determine the potential for habitability – now, or in the past.

Callisto has the oldest known surface in the solar system.  It appears heavily cratered, an indicator of its age, and is inactive (no volcanos on Callisto!).   Given its age it will help us explore the history of our own solar system.  It may also contain a salty subsurface ocean, something else the sensors on board Juice will be looking for.

After launch (hopefully!) in April, Juice will then set off on its eight-year cruise out to Jupiter.  On the way it will have to brave harsh radiation and temperature environments (+250C at Venus flyby, -230C at Jupiter!), but it has been designed to cope with all this.  For its science operation phase it will be a long way from Earth, so it will need a powerful antenna to send back data, and largely autonomous systems due to the time delay.  Sunlight is 25 times weaker at Jupiter than on Earth, so it also has very large solar panel arrays (an area of 85 square metres!) producing 700-900 Watts (plus batteries for use during eclipses).

Jupiter will be a busy place over the next decade or so.  Juno is already in orbit, mapping Jupiter’s gravity and magnetic fields, and NASA are also sending Europa Clipper which will arrive in 2030and will work in collaboration with ESA’s Juice.  Keep an eye out for results from these missions!

For much more on Juice, its instruments and mission goals, see ESA’s Juice Launch Kit.

Remembering the Queen

Even when you know a death is coming, it is still a shock.  Along with the rest of the country, and with many around the world, I was very sad to hear the news last night that the Queen had died at Balmoral.  In a way, it was good to know she died somewhere she felt at home, surrounded by her family.  May we all be so lucky.

Seventy years on the throne is quite something.  She was one year younger than my grandad, so reading back through his memoirs is a reminder of how much the world has changed over her reign.  Her dedicated life of service was an inspiration to many and made her a powerful role model.  You may not be a supporter of the monarchy, but you can’t deny that.

My grandad met her once, when they were both young children.  During his early life, my grandad’s parents ran a farm at Dinnet, not far from Ballater.  The landowner and local member of parliament was friendly with the royal family who would often visit Dinnet House when they were in residence at Balmoral.  On one occasion, when a visit coincided with the strawberry crop, the young princesses came with a driver to the farm to collect some fresh cream from the the dairy.  While waiting for the cream, the princesses and their governess got out of the car to look at the young calves in the next field and my grandad and his sister joined them.  In his memoirs, my grandad notes that “they were young children just like we were, but very much tidier in appearance, and rather better spoken“.

I can understand the Queen’s love for Balmoral and the area.  If you’ve never been, it really is worth a visit.  Lochnagar is an imposing mountain and the scenery in the area is just gorgeous.  Last time I was there the gardens were coming to life in early spring, and we saw a red squirrel scrambling nervously up a tree near the gates.  The river Dee runs through the grounds of the estate and the colours of the granite rocks in the water inspired the design of the Balmoral tartan.  (The whiskey from the local distillery isn’t bad, either.)

Many decades later, I met the Queen too.  The merger of UMIST and the Victoria University of Manchester necessitated a new royal charter, which was presented by the Queen at the University on October 22nd 2004.

The Queen shaking hands with PhD students Paul Carr and Megan Argo.

The Queen meeting representatives of the faculty of Engineering and Physical Sciences during the ceremony to mark the granting of the new Royal Charter to the University of Manchester, 22nd October 2004.

I didn’t get to hear the speeches as I had been asked to be one of two representatives from the faculty to meet the Queen after the ceremony and talk to her about the research going on at the University.  We were briefed before hand and were very nervous, but she was (as many people have noted) extremely good at putting people at ease.  I’m sure you would get good at that too, with such a full diary of public engagements spanning decades.

Grandad kept a photo of the occasion on a shelf for years.  He also noted in his memoirs (and told me on several occasions) that he was “disappointed that Megan did not tell the Queen (as I told her to) that she was looking forward to becoming her Astronomer Royal“.  Sorry grandad, I don’t think that was ever even remotely likely!

Along with many, many people, I feel there is something missing today.  The Queen has been there my entire life; we all knew she wouldn’t last forever, but it is still strange to think she has gone.  Having lost two members of my own family this year, my thoughts are with the royal family today.

Rest in peace, Your Majesty, thank you for everything.

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.

British Empire Medal ?

Well, I’m pretty speechless.

When I first started delivering virtual planetarium shows to Brownie groups back in the lockdown of January 2021, I never expected how popular they would be.   Seventy shows and more than 1400 girls later, I’m still getting requests.  Not at the level I did during the pandemic, since groups have returned to meeting in-person, but I’m still delivering shows to groups (and schools!) I could never visit physically because of the distance, and having a lot of fun doing it.

I’m astonished to say that in the Queen’s Birthday Honours list published today I have been awarded the British Empire Medal for services to Girlguiding during the Covid-19 pandemic, in recognition of my efforts to help girls earn their Space interest badges during the pandemic, and for being a role model showing girls that science is fun and that they can be scientists if they want to be.

I don’t know who it was that nominated me for this, but a HUGE thank you to whoever it was!  It is always a real pleasure to talk with enthusiastic groups about astronomy and share my passion with them, and that is a brilliant reward in itself.  The questions asked by all the Rainbows, Brownies, Guides and Rangers I have spoken to over the last year and a half have been brilliant, and it’s been such fun answering them all!

If you want a show for your class or group, just fill in the form here – all you need is a laptop, projector, and a wall or screen to project me on to!


Nothing to see here – how satellites are ruining our shared skies

Have you ever camped somewhere quiet? Pitched your tent, carefully lit a small fire, watched the stars appear as the sky goes dark, picked up your phone to ask the internet if that’s Venus you can see – and then realised there’s no signal? With several private companies racing to develop the first operational space-based WiFi network, this could soon become a thing of the past – but so might your view of the stars.

Since the 1950s, humans have been launching satellites. From the early days of the space race the technology has developed dramatically, with satellites today carrying out tasks from communication to earth observation, measuring everything from ice coverage and wildfires, ocean currents and weather, to enabling the tracking of land use changes, predicting droughtsand spotting leaks from gas pipelines.

Arguably, the next logical step is a network of satellites providing global, universal internet access, and many companies are working on developing exactly this. These networks of satellites, known as constellations, will provide relatively cheap, low-latency and accessible internet to anyone on Earth. This will be particularly beneficial for remote locations where the potential benefits of internet access would be significant for human and economic development but cost of installing fibre is prohibitive.

Affordable, universal internet coverage enables fast, reliable communication, transcending socio-political boundaries, bridging the digital divide and helping people everywhere access education and reducing global inequality.

Is there space in space?

There is clearly huge potential, and lots to be gained. But is there enough room in low Earth orbit? According to data maintained by the UN Office for Outer Space Affairs, there are currently 8,221 satellites in Earth orbit, though less than half are operational. In total since the 1950s, humanity has launched more than 12,000 satellites into space. The number of objects launched in a year doubled between 2016 and 2017, and in 2021 alone we launched 1,800 objects. Including debris fragments, there are over 23,500 objects larger than 10 centimetres in size currently orbiting the Earth.  The accidental collision in December 2021 of the Chinese meteorological satellite, YunHai 1-02, with debris from a rocket launched in 1996 really hasn’t helped matters.  Neither did the Russian anti satellite test back in November that deliberately created a cloud of over 1,500 pieces of debris that threatened the International Space Station.

Space may be big, but the available space in Earth orbit is finite. Satellites have to avoid each other, they must communicate with other satellites in their networks and with those on the ground without interfering with each other, and we need to know accurately where they all are to avoid collisions. These are significant challenges; the safe use of Earth orbit requires cooperation.

Each of the companies developing these networks is planning and launching its own constellation, consisting of several hundred (and up to tens of thousands of) individual satellites. If we want to provide cheap, accessible internet to every community, then we will need to safely launch and operate many tens of thousands of satellites. How do we ensure this is done in a sustainable way?

The UN Committee on the Peaceful Uses of Outer Space produced guidelines on the sustainability of outer space activities, covering the avoidance of contamination (both of other planets and of the Earth), the safe re-entry of defunct satellites, sustainable use of the (finite) radio spectrum, the sharing of space weather and forecasting, among other things. However, these are guidelines, not laws, and are voluntary. Going forward, and in order to protect both the space around the Earth, the safety of the people on it and their view of the universe, we need international cooperation and agreement.

Blinded by the light

What about that view of the stars from our campsite? In good conditions we can see a total of around 10,000 stars with the naked eye, spread across both hemispheres. The darker your location, the more stars you can see. Over time our night skies have become brighter and brighter, with every new streetlight or security light making the stars harder to see. As a consequence, astronomical telescopes are confined to remote places, often on the tops of isolated mountain peaks.

However, this dramatic increase in satellite numbers now threatens these facilities and the science they enable. New constellations are launching at a time when several large, multi-country, expensive telescopes are under construction or becoming operational. The problem with the proliferation of satellites is that it becomes impossible to avoid them when trying to observe the universe. At least one of these companies is working with astronomers to try to minimise the effects on observations, but there is no regulatory compulsion to do so.  The big science questions these telescopes were built to address will become impossible to answer if we can no longer see the sky properly.

One telescope at risk is the Vera C. Rubin Observatory, a large optical telescope with a 3.2 gigapixel camera under construction in Chile, which aims to rapidly scan the sky to search for transient astronomical events and asteroids, among other things. This telescope should see first light this year, but will be particularly adversely affected by the extreme photobombing caused by large numbers of satellites passing through its large field of view.

It isn’t just optical telescopes that will suffer, either. For current and future radio telescopes, the proliferation of transmitters in orbit will make trying to observe the universe like trying to hear a violin over the sound of a jet engine. The cosmos will become as invisible to radio telescopes as the stars are to the human eye during the day.

Now, no astronomer is arguing against the human and economic benefits of universal internet (astronomy itself is being used as a basis for development projects around the world), but there is concern that this will ruin the view for everyone, and render much of modern astrophysics impossible in the long term. This ultimately leads to a waste of taxpayers’ money, a loss of training opportunities in the high-level technical and analytical skills that astronomy provides (most astronomy graduates do not become astronomers, but work in IT, business and the civil service, where they put those analytical skills to good use), and a loss of part of our shared cultural heritage.

One solution is obvious: we could just send all our telescopes into space. That’s fine if you have the money to do it, and it does happen (the Hubble Space Telescope and the James Webb Space Telescope being the best-known examples). In practice, this is always a more expensive option, it is a lot more risky, if something goes wrong it is difficult to fix, and you can’t build your telescopes as big for the same amount of money. This may be the long-term future of astronomy, but we are a long way from that being normal. It also does nothing for the view from our campsite.

Don’t look up?

For the moment, these constellations are being launched only with the go-ahead from country-based agencies (mainly in the US), but they impact the whole planet’s view of the universe. The night sky and the space around the Earth can (and, perhaps, should) be thought of as a natural wilderness and protected as such for everyone to enjoy and use, but that requires serious international cooperation and agreement – which, at present, does not exist.

Having internet access can drive economies forward and provide an excellent gateway to education. Is protecting the night sky for the minority of those who want to look at it (including amateur astronomers and children) more important than providing affordable internet in remote areas? Definitely not, but if we want to preserve the night sky for future generations, we need to act now. After all, if we can’t see the sky, we might not find the next incoming comet or asteroid until it’s too late.

[This article was originally published in Green World on July 7th 2020.  The numbers have been updated.]

OMG an ASTEROID the size of the EIFFEL TOWER!!!

You might have spotted the story in the media yesterday about an asteroid called Nereus which makes a close approach to the Earth today.  It’s described as the size of the Eiffel Tower and will zip past us pretty close, coming within 3.9 million kilometres.  Are we all doomed?  Of course not.  Here’s why.

Asteroid Nereus (or to give it its full designation, asteroid 4660 Nereus) is a lump of rock about 330 metres in diameter.  It was discovered in 1982, about a month after it passed within 4.1 million kilometres of the Earth.  It’s not spherical, more egg shaped, according to radar observations.  In late 2001/early 2002, astronomers used a radio telescope at Goldstone to send radio waves at the asteroid during one of its previous close approaches, using the reflected signals to measure its size and shape.  They found that it has dimensions of  510 by 330  by 241 metres, and it rotates on its own axis every 15 hours or so.

There are actually many thousands of lumps of rock this size in the inner solar system.  None of them are known to be on a direct collision course with the Earth, but we haven’t found all of them yet – not by a long way.  The current count of known asteroids is 1,113,527 (according to this NASA page), and this number is increasing all the time as we find more of them.  Some of these space rocks are large and easy to spot from Earth, but most are much smaller and are quite hard to find.

The problem with hunting for asteroids is that they are mostly (a) small, and (b) made of rock.  Small things reflect less sunlight, so they are fainter and need a bigger telescope to spot, and things made of rock tend not to be terribly reflective.  You’ve probably seen snow on mountains – the snow is much brighter than the rocky areas because white things reflect more sunlight than black/brown things.

Nereus is quite reflective for a rocky asteroid, but still tricky to spot because of its small size.  One estimate puts its maximum apparent magnitude (how bright it will appear to an observer on the Earth) at 12.6 which is pretty faint.  If you are lucky enough to live somewhere with dark skies, you can probably see stars an faint as about magnitude 6.  [This is one of those annoying astronomical measurements that doesn’t make intuitive sense – bigger numbers relate to fainter objects, so the Sun has an apparent magnitude of -26.74 while faint distant galaxies can have magnitudes of +20 or more.  The scale is also logarithmic as well, which  means that a difference of one magnitude is actually a factor of 2.5 in brightness.]  At its brightest, at closest approach, Nereus will be magnitude 12.6 which is more than 400 times fainter than the faintest stars you can see unaided.

Now, most of these floating space rocks are never likely to cause us a problem.  They orbit the Sun in the asteroid belt, a region between Mars and Jupiter where there is a concentration of asteroids.  Not all of them are in the asteroid belt though, many have elliptical orbits around the Sun, rather than the almost circular orbit of the Earth, and sometimes those orbits can bring an asteroid close to the Earth.   (The trick is to spot them coming!)

Nereus has an elliptical orbit within the inner solar system, taking 1.8 years to complete each orbit.  This orbit causes it to pass close to the Earth from time to time, but it also comes pretty close to Mars as well.  This actually makes it an excellent candidate for a sample return mission, and it was originally one of the candidates for the Hayabusa mission – but a delay meant that probe ended up visiting asteroid Itokawa instead.

OK, that’s the science background.  Should we worry about it coming so close?

Well, first some perspective.  At its closest on this occasion, Nereus will be 3.9 million kilometres from the Earth – that’s about ten times the distance between the Earth and the Moon.  Just on that count, we don’t really have anything to worry about.  This distance may be small when you compare it to the size of the entire solar system, but it’s still a long way.  Nereus will actually come even closer in the future; in 2060 its orbital path will bring it within 1.2 million kilometres of Earth.  That’s three times the Earth-Moon distance, so still not a threat.  If you are interested, here are the predictions for future encounters (including a close approach to Mars in 2089.

So no, we don’t need to worry.

I’ve talked about other asteroids though, and how the inner solar system contains an awful lot of them.  If we didn’t spot this one until it was already a month past a close approach, how easy might we miss another one that might come closer?  Well this is a risk.

In planetary terms, an asteroid impact could potentially do a lot of damage.  How much damage depends on the size of the impactor, the relative velocity of the asteroid and the Earth, and what the asteroid is made of.  There are lots of impact simulators around, but this one suggests that a collision with a 330-m object on land would result in a crater more than 4 km in diameter, and an earthquake of magnitude 7.8.  Their estimate is that an impact on this scale occurs on Earth (statistically) every 18,000 years.

There are plenty of efforts ongoing to find these asteroids and determine their orbits.  Many telescopes do this sort of work, and it’s something the Vera C. Rubin Observatory will be able to do really well (if the light from all the satellites being sent into low Earth orbit doesn’t cause too much of a problem… but that’s a topic for another day).

If we do find an asteroid that could impact the Earth, we need to have some way of dealing with it.  We can’t rely on Bruce Willis, so just last month NASA launched the DART mission to the binary asteroid system Didymos and its smaller companion Dimorphos.  The idea with DART is to test planetary defence techniques by, well, literally smashing a 500 kg projectile into Dimorphos at ~6.6 km/s (~15,000 mph) and watching how its orbital path changes.

The physics is simple (its just conservation of momentum) and, if all goes well, following the impact in October 2022 we should be able to observe a small change in the orbital period of Dimorphos.  It’s not the first time humans have visited as asteroid, and it’s not the first time we’ve deliberately bashed into one, but it is the first time we’ve actively tried to alter the trajectory of a solar system object.  If we do spot something dangerous headed our way, it makes sense to know how to make it less of a threat!

So, should we worry about Nereus?  No.  Categorically no.  It’s not a threat.  Should we worry about something we haven’t spotted yet hitting us in the future?  Well, it’s unlikely, but we really ought to be expending some resources to look.  It’s in our own interest as a species, after all.

Don’t have nightmares.

Ever wanted to design a space patch?

After all the fun with the planetarium shows, a couple of us at UCLan hatched a plan to ask kids to help us design a new Space Badge for Alston Observatory.  We get a lot of Cub and Scout groups visiting the Observatory, but far fewer groups of Brownies or Guides.  Cubs and Scouts have Astronomer badges, and Brownies have a Space badge, but Guides don’t (sadly).  But, everyone loves a good badge for their backpack/camp blanket/whatever!  So, we’re asking people between the ages of five and sixteen to get creative and help us design a new Space patch that we will get made up and give out to young visitors to our Observatory.  Know someone creative in the right age group?  Ask them to get their pencils out!  Hurry though, entries close on October 31st.

University of Central Lancashire

Calling all space fans aged 5-16 years old!

Use your artistic skills to design a space badge – from stars to planets, telescopes to extra-terrestrial life, create your design to inspire future space explorers.

The winning designs will be given out to Alston Observatory visitors.

The winner will receive a £30 Amazon voucher and there are books for the runners-up.

Competition closes 31 October 2021.

Ask your parent / guardian to review the full T&C’s.

Download an entry form

University events are returning including the Lancashire Science Festival

Lancashire Science Festival

Best wishes,
The Lancashire Science Festival Team
University of Central Lancashire

#LancSciFest / LancSciFest

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So. Many. Brownies.

As I said in an earlier post, I’ve been offering free virtual planetarium shows via Zoom to Brownie and Guide groups around the UK since January 2021.  This all started when a friend of mine (a daughter of my old Guide leader) asked if I could do something for her Brownie group – I’d visited them in person before and taken a telescope, getting all the Brownies through their space badge in one evening.

I figured that a virtual planetarium show using Stellarium would work pretty well over Zoom, so on a cold January evening I joined their meeting and took them on a tour of the evening sky, told them the story of Andromeda and Perseus, and then we visited some of the planets.  They asked a lot of questions!  The evening was such a success that I decided to offer it to other groups during lockdown.  One Facebook post later and I was absolutely swamped with requests!  I’ve been doing shows ever since.

It’s now eight months on, and as we pass the end of another term and groups have broken up for the summer, it’s a good time to look back and take stock.

From that first event, the idea developed into one of the most successful public engagement projects I’ve ever run.  With a budget of £0, and the help of three of my colleagues I had to draft in to help me cope with the volume of requests, we’ve managed to reach over 1,200 girls around the country, through 60 individual shows, from Portsmouth to Clackmannanshire, Caernarfonshire to Yorkshire, and everywhere in between.

At UCLan we have an Observatory where we teach undergraduate astrophysics classes, but we also host public events for families, youth groups, and the general public.  We get a lot of Scout and Cub groups coming along, but very rarely do we get any Guide or Brownie groups visiting, despite the Brownies having a recently revamped Space badge in the programme.  It’s not hard to see why this is; girls are often perceived as being less interested in this sort of thing, and maybe it’s not something the leaders think of doing with the girls.

But my experience over the last few months is that Brownies absolutely love space!  In fact, my experience with hundreds of schools and youth groups across the UK and Australia over the last 18 years (since I started doing public engagement during my PhD studies…) is that most children love space, at least to some extent.  Space and dinosaurs.  And I love answering their questions.  Even when science hasn’t found the answer yet!  (That’s half the fun of science, after all!)

I’m not aiming to create a huge number of budding astrophysicists, or even scientists – that is unrealistic – but if I can inspire just a few kids to take an interest in science, maybe develop an appreciation for it and keep being curious about the world around them as they grow up, then I will have achieved something.

If you are reading this and want a virtual visit for your group from September 2021, here’s the booking form.  Best efforts though, I only have so many free evenings ☺️

The research/teaching dichotomy: why do we have to choose?

If you are reading this, you are probably aware that I’m an astrophysicist.  I’m a research scientist with a bunch of academic publications to my name, including my (little-read) PhD thesis from 2006.  I’m also lucky enough to have landed an academic job where I can do research and teach.

When I started out on this career path, waaaaaay back at primary school (yes, really, I was one of those annoying kids who knew early on what they wanted to do) I was warned by many people that it would be difficult, and that very few people succeeded.  Someone gave me a leaflet published by the RAS (I think) that ran through the numbers and showed how few of those aspiring to be astronomers actually got a job in the field.  I’m very lucky.

But from a fairly young age, I also realised I was good at teaching stuff to other people.  Whether that was lighting fires on Guide camp,  teaching my older relatives how to use a computer, or any number of other things, people often told me I would make a good teacher.  It was a long time before I believed that they were right.


As a PhD student, you are encouraged to do a  bit of teaching, as a means of income if nothing else, but not given much training in how to do it, never mind how to do it well.  At least, I wasn’t, they just let you get on with it.  Many students emulated the behaviour of their professors because if that’s all you have seen of teaching in HE, it’s what you think good teaching is.  Even if it isn’t.

As an aspiring academic I could see that, in UK higher education at least, there was an increasing trend for new academics to do training in how to teach, often in the form of a PGCertHE.  As a postdoc, I was enthusiastic about this – it surprised me to discover that there were no formal requirements for teacher training in universities.  I spent two years teaching in the lab.  I wrote and delivered an MSc-level course in radiation processes in astrophysics.  I supervised internship and research students.  But when I tried to sign up for the PGCert at my institution, I was told that I couldn’t because I wasn’t an academic and therefore didn’t have any teaching responsibilities.

Hmm.  The qualification was increasingly becoming a requirement on academic job descriptions.  But I wasn’t allowed to do the qualification because I wasn’t already (formally) teaching.  I wasn’t allowed to (formally) teach because I was being paid purely to do research.  Stalemate.

Then I moved institutions to a job with actual teaching responsibilities.  Great, I thought, I’ll finally get to do some teacher training!  But no, I was told I couldn’t enrol on the PGCert because I didn’t have enough experience(!) and had to complete a different programme first.  That programme ran on a Thursday afternoon.  When I was teaching.  Not surprisingly, I failed the assessment because I hadn’t been able to get to any of the training sessions.

Why am I telling you all this?  Well, in February I finally started studying for a PGCert.  Ten years after I first tried.  In two months I will (hopefully!) have completed my final assignment and passed.  Thanks to a supportive boss, I was able to choose a PGCert that was particularly relevant to what and how I teach, and have my fees paid for through the staff development fund.  But it really bugs me that it’s been so hard to get to this point.

I’ve come across a large number of academics who consider teaching to be trivial, or an inconvenience, or something they just have to do to keep their job.  Maybe that is peculiar to physics, but I doubt it somehow.

Some of us are really passionate about both teaching and research.  It seems to be difficult to do both, and give them both the time and attention they require.  Promotion criteria seem to work against use here, too.  You can follow the traditional “academic” pathway where your research is highly valued, or you can follow the “teaching” pathway where you are expected to not put any effort into advancing your field any more.

Why should we choose?  Why can’t we do both?  Teaching informed and inspired by research is more satisfying for students, and for lecturers.  And research informed by teaching can provide inspiration and potentially take you in new directions.

As Fabrice Hénard and Deborah Roseveare said in one of the recommendations set out in their report for the OECD’s Institutional Management in Higher Education, Fostering Quality Teaching in Higher Education: Policies and Practices, universities should:

“Cross-fertilise professional development for teaching and research so as to increase mutual learning. Avoid distinctive professional development paths.”

I couldn’t agree more.

As Amy J. Ko discusses over here, research and teaching are both more powerful when they are woven together.  If the future of higher education is to stay relevant to the world around us and give our students the skills and tools to fix the Big Problems like climate change, we need to be teaching them how to find reliable information, think critically, synthesise information and ideas and discover creative ways to solve problems.

I don’t know about you, but to me that sounds like the same set of skills it takes to do research.

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