Who's afraid of big, bad numbers? In the show this time, we talk to Bobby Seagull about the mathematics of astronomy and popularising maths among the public, Michael Wright rounds up the latest news, and we find out what we can see in the December night sky from Ian Morison, Haritina Mogosanu and Samuel Leske.
The News
This month in the news: The potential discovery of a new fundamental force carrying particle, and exploring the possibility of planets orbiting black holes.
Firstly it is worth discussing the claim of a 5th force of nature, what has been called the X17 particle. In the standard model of particle physics forces arise from what is known as a force carrier. For example, photons for electromagnetism and Gluons for the strong force.
Another interesting piece of news is a theoretical paper by Keiichi Wada, Yusuke Tsukamoto, and Eiichiro Kokubo titled Planet Formation around Supermassive Black Holes in the Active Galactic Nuclei . As this suggests, the paper is about the idea of finding planets around supermassive black holes. The notion is not as surprising as it may sound, since we know that discs of gas and dust, from which matter clumps together to form planets, could exist around black holes. Supermassive black holes, for instance, have been observed to be surrounded by a torus of dust, with cold dense gas forming a thin disc shape. The paper attempts to predict mathematically which types of AGN could facilitate planet formation by inserting various system parameters (say, black hole mass) into standard planet formation models.
Interview with Bobby Seagull
Emma Alexander and Joe Hanson conduct an extended interview with Bobby Seagull, known for his appearances on University Challenge and Monkman & Seagull's Genius Guide to Britain. They talk about the mathematics of astronomy, and in particular about the difficulty of conceptualising, nevermind conveying, the magnitude of the scales involved in astronomy. Bobby also talks about his efforts towards helping ordinary people overcome an aversion when it comes to maths, which is the subject of his PhD thesis.
The Night Sky
Northern Hemisphere
Ian Morison tells us what we can see in the Northern Hemisphere night sky during December 2019.
The Planets
- Jupiter, shining on the 1st at magnitude -1.8 and with an angular size of 32 arc seconds, can be seen very low in the southwest as darkness falls at the start of December but, soon after, will be lost in the Sun's glare. Jupiter lies in the southeastern part of Ophiuchus and is heading towards the southernmost part of the ecliptic so, as it appears in the twilight, will only have an elevation of ~6 degrees. With its low elevation, atmospheric dispersion will take its toll and an atmospheric dispersion corrector would greatly help to improve our views of the giant planet and it four Gallilean moons.
- Saturn will be seen west of south as darkness falls at the start of the month. Then, its disk is ~16 arc seconds across and its rings - which are still, at ~24 degrees, nicely tilted from the line of sight - spanning some 36 arc seconds across. During the month its brightness remains +0.6 with an angular size of 15.4 arc seconds. Sadly, now in Sagittarius and lying on the south-eastern side of the milky way, it is at the lowest point of the ecliptic and will only have an elevation of ~12 degrees after sunset. As with Jupiter, an atmospheric dispersion corrector will help improve our view.
- Following its transit of the Sun and reaching greatest elongation west on the 28th of November, Mercury can be seen in the pre-dawn sky low in the southeast at the start of December. On the 1st it will have a magnitude +0.29 and will rise around an hour before the Sun. It will then have an elevation of some 9 degrees before being lost in the Sun's glare. With an angular size of ~5 arc seconds, it will then fall back towards the Sun and be lost from view by the middle of the month.
- Mars can be seen towards the southeast in the pre-dawn sky at the start of its new apparition. It rises some two and a half hours before the Sun at the start of the month and will have an elevation of ~15 degrees before it is lost in the Sun's glare. It then has a magnitude of +1.7 and a 3.9 arc second, salmon-pink, disk. By month's end it will be seen further round towards the south before dawn and its magnitude will have increased slightly to +1.6.
- Venus may just be glimpsed in the south-west at the start of the month, but will be difficult to see due to the fact that the ecliptic is at a shallow angle to the horizon and so Venus will have a very low elevation. As the month progresses, it will rise higher in the sky and on the 31st will have reached an elevation of 14 degrees as darkness falls. During December, its magnitude remains at about -4 and its disk increases from 11.6 to 13 arc seconds across. A low horizon and possibly binoculars will be needed to spot Venus, but please do not use them until after the Sun has set.
- November - still a chance to observe Saturn. The thing that makes Saturn stand out is, of course, its ring system. The two outermost rings, A and B, are separated by a gap called Cassini's Division which should be visible in a telescope of 4 or more inches aperture if seeing conditions are good. Lying within the B ring, but far less bright and difficult to spot, is the C or Crepe Ring.
- December, late evening: the Double Cluster and the 'Demon Star', Algol. December is a good time to look high in the Southeast after dark towards the constellations of Cassiopea and Perseus. Perseus contains two interesting objects; the Double Cluster between the two constellations and Algol the 'Demon Star'. Algol in an eclipsing binary system. Normally the pair has a steady magnitude of 2.2 but every 2.86 days this briefly drops to magnitude 3.4.
- December: find Uranus. This month is a still good time to find the planet Uranus in the late evening as it reached opposition on October 28th. With a magnitude of 5.7, binoculars will easily spot it and, from a really dark site, it might even be visible to the unaided eye. A medium aperture telescope will reveal Uranus's 3.7 arc second wide disk showing its turquoise colour. It lies in Aries, close to the boarders of Pisces and Cetus as shown on the chart.
- December: find M31 - The Andromeda Galaxy - and perhaps M33 in Triangulum. Around new Moon (26th December) - and away from towns and cities - you may also be able to spot M33, the third largest galaxy after M31 and our own galaxy in our Local Group of galaxies. It is a face on spiral and its surface brightness is pretty low so a dark, transparent sky will be needed to spot it using binoculars (8x40 or, preferably, 10x50). Follow the two stars back from M31 and continue in the same direction sweeping slowly as you go. It looks like a piece of tissue paper stuck on the sky just a bit brighter than the sky background. Good Hunting!
- December 1st. If clear before dawn and looking southeast, one could see a nice lineup of Mercury, Mars and Spica. Arcturus will be seen high up to their left.
- December 10th. In the evening one could see the Moon, close to full, lying between the Pleiades and Hyades Clusters. Aldeberan is a red giant star far closer to us.
- December 12th - before dawn: Mars and the double star Alpha Librae. If clear before dawn on the 12th, one will see Mars (magnitude +1.67) just above the double star Alpha Librae (Magnitudes +2.74 and +5.15) or Zubwnelgenubi. Despite its name it is the second brightest star in Libra. This would make a nice image using a small telescope.
- December 14th and 15th after midnight: the Geminid Meteor Shower. The early mornings of December 14th and 15th will give us the chance, if clear, of observing the peak of the Geminid meteor shower. The Moon is at First Quarter and will set around 11 pm so, when Gemini is highest in the sky, its light will not hinder our view. The Geminids can often produce near-fireballs and so the shower is well worth observing if it is clear. An observing location well away from towns or cities will pay dividends. The relatively slow moving meteors arise from debris released from the asteroid 3200 Phaethon. This is unusual, as most meteor showers come from comets. The radiant - where the meteors appear to come from - is close to the bright star Castor in the constellation Gemini as shown on the chart. If it is clear it will be cold - so wrap up well, wear a woolly hat and have some hot drinks with you.
- December 22nd/23rd - late evenings: the Ursid Meteor Shower. The late evenings of the 22nd and 23rd of December are when the Ursid meteor shower will be at its best - though the peak rate of ~10-15 meteors per hour is not that great. Sadly, this year Full Moon is on the 21st, so its light will greatly hinder our view. The radiant lies close to the star Kochab in Ursa Minor (hence their name), so look northwards at a high elevation. Occasionally, there can be a far higher rate so it is worth having a look should it be clear.
- December - Evenings of the 5th and 18th: The Straight Wall. The Straight Wall, or Rupes Recta, is best observed either 1 or 2 days after First Quarter or a day or so before Third Quarter. To be honest, it is not really a wall but a gentle scarp - as Sir Patrick has said "Neither is it a wall nor is it straight!"
- Where we are.
This time we went to Stonehenge Aotearoa, but don't worry this is still in the Southern Hemisphere. Stonehenge Aotearoa is the centre for archeoastronomy in New Zealand. There is a beautiful observatory built there with ancient knowledge and modern technology - such as surveyors and cement. There is literally a stone henge, there are stones that mark the rising and setting of the Sun at solstices and equinoxes, it is an amazing place in the middle of the most amazing dark sky that the North Island of New Zealand can provide. And since is not far away from Wellington, we had the chance to drive there and do some proper stargazing. Here is what's in the store for December.
- Overview of the night sky.
For those of us who don't read the instructions, we just have some amazing stuff that we wish to share and those who do neither instructions nor stories, here's the gossip. Did you know there's going to be a meteor shower in December's night sky? And a Full Moon? The Moon will do what the Moon does, going close by all the visible planets in the sky so we will talk about when that happens.
And also we will experience the Summer Solstice when we will have the longest day. Also, our second interstellar visitor, comet 2I/Borisov, is at its closest approach to Earth later on in December. The idea of this show is that you will get your stargazing thing on and get observing. We've been trying to keep up with that so for the last few weeks, every weekend we take our telescopes and go to a dark sky location. There are plenty of these in New Zealand. - Orion.
Look for Orion on the eastern horizon, as it reappears in the night sky. For the next half year the sky will be dominated by bright stars, and not so much the Milky side of the Milky Way. The cool thing is that this time of the year we will be able to see in one go the brightest, second brightest and third brightest stars in the sky: Sirius, Canopus and Alpha Centauri.
Look for Sirius, the Dog star to the right of Orion's belt on the same line. If you stretch your arm and stretch again all your fingers, it would be the distance from your thumb to your pinky, approximately 20 degrees. Canopus, the cat star and the second brightest star in the sky is about 30 degrees from Sirius, and about the same distance from the horizon. On the same line with Orion's belt and Sirius about 60 degrees right from Sirius is Alpha Centauri, the third brightest star in the sky and our closest neighbour. So these stars: Orion's belt, Sirius and Alpha centauri are almost at the same height when Orion's belt is almost parallel with the ground.
On the other side from Orion's belt, same distance as Sirius, look for red giant Aldebaran, which is visually part of the constellation of Taurus and then, with your arm stretched, three fingers left from that you will discover the Pleiades. Keep going to the left you will come across the great square of Pegasus. Just to the right of it, is the Andromeda Galaxy, for those lucky enough to have clear northern horizon. So this time of the year, if you can stretch it, from the Southern hemisphere not only you can see the first 3 brightest stars in the sky (including our closest neighbour) but you can also spot 4 galaxies with the naked eye - that's about the maximum number of galaxies that you can spot with the naked eye anyway.
Look for the planets in the same part of the sky where you would look for the Sun or the Moon, this is called the ecliptic.
- The Planets
Mars and Mercury are in the morning sky. In December, Mercury will reach its highest point in the morning sky. Mars is in the morning sky too. Between the two of them, you should be able to see Mars in the second half of the month or if you have a clear horizon.
In the evening sky, Look for Orion, Taurus, Eridanus and constellations that are neighbouring Eridanus on the South Celestial Circle, they are now visible. On the ecliptic, looking counterclockwise are Aries, Pisces, Aquarius and Capricornus.
Venus and Saturn will have a close encounter on the 11th of December, look west to see them just after sunset. Have a good look as the next day it will be full Moon, which will light pollute the skies.
- Meteor Showers
There might be a meteor shower or two visible: Firstlythe Puppid-Velids at the beginning of December. SecondlyThe Geminids - but not so visible from here as Gemini will still be low on the horizon unless you're burning the midnight oil. Look for this meteor shower anytime between 7 and 17 of December The radiant (the point in the sky that seems to rain stars) is in the constellation Gemini. The trick with that is not to look at it but away from it, try to see if you can spot any with your peripheral vision.
- The Moon
Speaking about the Moon, best time for stargazing is in the second part of the month.
The Moon will be at first Quarter on the 4th of December. It will reach apogee on the 5th of December (that is its furthest point from Earth) then aphelion (furthest point from the Sun) on the 11th of December, then it will pass close to the Pleiades on the 16th of December. It will reach perigee (the closest point to the Earth) on the 19th of December when it also will be at last quarter.
On 22 of December we celebrate the Summer Solstice here in the Southern Hemisphere, the longest day.
The next day, the Moon will pass close by Mars (on the 23rd of December).
There will be an annular eclipse of the Sun visible from Oceania (But not NZ) on the 26 of December. The Moon will reach perihelion on the 27th of December, will get close to Saturn on the 28 and close to Venus on the 29th of December. Venus by then had reached the highest point in the evening sky.
Up close to zenith, in December you will see Piscis Austrinus, Grus, Sculptor, Phoenix, and Fornax.
Since December is the month of major celebrations, we think a star party might be in order.
Keep an eye on our interview with Richard Hall and Kay Leather from Stonehenge Aotearoa.
We wish you happy hunting for galaxies this month, and if all that doesn't work then grab yourself a couple of craters on the Moon.
- Clear skies from Haritina and Sam from New Zealand, and see you next year!
Highlights
Southern Hemisphere
Haritina Mogosanu and Samuel Leske from the Carter Science Centre in New Zealand speaks about the Southern Hemisphere night sky during December 2019.
Odds and Ends
We give a brief update on the developments surrounding the Thirty Meter Telescope, the construction of which is being protested due to the planned location of Mauna Kea being held sacred by some Native Hawaiians.
Show Credits
| News: | Michael Wright |
| Interview: | Emma Alexander, Joe Hanson, and Bobby Seagull |
| Night sky: | Samuel Leske, Ian Morison and Haritina Mogosanu |
| Presenters: | George Bendo, Phoebe Stainton, and Hongying Chen |
| Editors: | Hongming Tang, Tiaan Bezuidenhout, Lizzy Lee, Joseph Winnicki, and Michael Wright |
| Website: | Tiaan Bezuidenhout and Stuart Lowe |
| Producer: | Tiaan Bezuidenhout |
| Cover art: | Logo for Matt Parker's 'Say no to mathematically impossible street signs!' campaign. CREDIT: Matt Parker |