Can Artificial Intelligence help find alien intelligence?

File 20180503 153884 1gegba7.jpg?ixlib=rb 1.1
Artist’s impression of Proxima b, a planet orbiting the star Proxima Centauri within the closest known star system outside of our solar system.
(ESO/M. Kornmesser), CC BY-SA

By Michael P. Oman-Reagan, Memorial University of Newfoundland

In the search for extraterrestrial intelligence (SETI), we’ve often looked for signs of intelligence, technology and communication that are similar to our own.

But as astronomer and SETI trailblazer Jill Tarter points out, that approach means searching for detectable technosignatures, like radio transmissions, not searching for intelligence.

Now scientists are considering whether artificial intelligence (AI) could help us search for alien intelligence in ways we haven’t even thought of yet.

‘Decoding’ intelligence

As we think about extraterrestrial intelligence it’s helpful to remember humans are not the only intelligent life on Earth.

Chimpanzees have culture and use tools, spiders process information with webs, cetaceans have dialects, crows understand analogies and beavers are great engineers. Non-human intelligence, language, culture and technology are all around us.

A capuchin (Sapajus libidinosus) using a stone tool (T. Falótico). An octopus (Amphioctopus marginatus) carrying shells as shelter (N. Hobgood).
(Wikimedia/Tiago Falótico, Nick Hobgood), CC BY-NC-SA

Alien intelligence could look like an octopus, an ant, a dolphin or a machine — or be radically different from anything on Earth.

We often imagine extraterrestrial life relative to our ideas about difference, but those ideas aren’t even universal on Earth and are unlikely to be universal across interstellar space.

If some of us have only recently recognized non-human intelligence on Earth, what could we be missing when we imagine extraterrestrial life?

In early 2018, astronomers, neuroscientists, anthropologists, AI researchers, historians and others gathered for a “Decoding Alien Intelligence” workshop at the SETI Institute in Silicon Valley. Astrobiologist Nathalie Cabrol organized the workshop around her 2016 paper “Alien mindscapes,” where she calls for a new SETI road map and a long-term vision for “the search for life as we do not know it.”

In her paper, Cabrol asks how SETI can move past “looking for other versions of ourselves” and think “outside of our own brains” to imagine truly different extraterrestrial intelligence.

Thinking differently

Silicon Valley is famous for valuing “disruptive” thinking and this culture intersects with SETI research. Ever since the U.S. government stopped funding SETI in the mid-1990s, Silicon Valley ideas, technology and funding have been increasingly important.

For example, the SETI Institute’s Allen Telescope Array is named after Microsoft co-founder Paul Allen, who contributed over US$25 million to the project. And, in 2015, technology investor Yuri Milner announced Breakthrough Listen, a 10-year US$100 million SETI initiative.

Now, the SETI Institute, NASA, Intel, IBM and other partners are tackling space science problems through an AI research and development program called the Frontier Development Lab.




Read more:
Why I believe we’ll find aliens – leading expert on search for intelligent extra-terrestrial life


Lucianne Walkowicz, the Astrobiology Chair at the Library of Congress, described one AI-based method as “signal agnostic searching” at Breakthrough Discuss in 2017.

Walkowicz explained that this means using machine learning methods to look at any set of data without predetermined categories and instead let that data cluster into their “natural categories.” The software then lets us know what stands out as outliers. These outliers could then be the target of additional investigations.

It turns out that SETI researchers think AI might be useful in their work because they believe machine learning is good at spotting difference.

But its success depends on how we — and the AI we create — conceptualize the idea of difference.

Smarter than slime mould?

Thinking outside our brains also means thinking outside our scientific, social and cultural systems. But how can we do that?

AI has been used to look for simulations of what researchers imagine alien radio signals might look like, but now SETI researchers hope it can find things we aren’t yet looking for.

Graham Mackintosh, an AI consultant at the SETI Institute workshop, said extraterrestrials might be doing things we can’t even imagine, using technologies so different we don’t even think to look for them. AI, he proposed, might be able to do that advanced thinking for us.

We may not be able to make ourselves smarter, but perhaps, Mackintosh suggested, we can make machines that are smarter for us.

In a keynote at this year’s Breakthrough Discuss conference, astrophysicist Martin Rees shared a similar hope, that AI could lead to “intelligence which surpasses humans as much as we intellectually surpass slime mould.”

First contact

If we met extraterrestrial slime mould, what could we assume about its intelligence? One challenge of SETI is that we don’t know the limits of life or intelligence, so we need to be open to all possible forms of difference.

We might find intelligence in forms that Euro-American science has historically disregarded: Microbial communities, insects or other complex systems like the symbiotic plant-fungus relationships in mycorrhizal networks that learn from experience.

Intelligence might appear in atmospheres or geology at a planetary scale, or as astrophysical phenomena. What appears to be a background process in the universe, or just part of what we think of as nature, could turn out to be intelligence.

Consider that the largest living thing on Earth may be an Armillaria ostoyae fungus in Eastern Oregon’s Blue Mountains, which extends to 10 square kilometres and is between 2,000 and 9,000 years old.

While this fungus may not be what most people think of as intelligence, it reminds us to think about the unexpected when searching for life and intelligence, and of what we might be missing right under our feet.

Parts of the Armillaria ostoyae organism include the mushrooms, the black rhizomorphs and the white mycelial felts.
(USDA/Forest Service/Pacific Northwest Region)

Thinking differently about intelligence means understanding that anything we encounter could be first contact with intelligent life. This might include our first encounter with artificial general intelligence (AGI), also called Strong AI, something closer to the sentient computer HAL 9000 from 2001: A Space Odyssey or Data from Star Trek: The Next Generation.

As we work with machine learning to expand the SETI search, we also need social sciences to understand how our ideas shape the future of AI — and how AI will shape the future of our ideas.

Interdisciplinary futures

To avoid a human-centred point of view in SETI we need to consider how we encode ideas about difference into AI and how that shapes the outcomes. This is vital for finding and recognizing intelligence as we don’t yet know it.

Some of the methods used in anthropology can help us identify ideas about difference that we’ve naturalized — concepts so familiar they seem invisible, like the divides many still see between nature and culture or biology and technology, for example.

Recent research on algorithms reveals how our naturalized ideas shape the technology we create and how we use it. And Microsoft’s infamous AI chat bot Tay reminds us the AI we create can easily reflect the worst of those ideas.




Read more:
Teaching chatbots how to do the right thing


We may never entirely stop building bias into search engines and search strategies for SETI, or coding it into AI. But through collaborations between scientists and social scientists we can think critically about how we conceptualize difference.

The ConversationA critical, interdisciplinary approach will help us understand how our ideas about difference impact lives, research and possibilities for the future both here on Earth and beyond.

Michael P. Oman-Reagan, Vanier Scholar, Department of Anthropology, Memorial University of Newfoundland

This article was originally published on The Conversation. Read the original article.

A giant ‘singing’ cloud in space will help us to understand how star systems form

File 20180510 184630 8kvekt.jpg?ixlib=rb 1.1
The dark band is the Dark Doodad Nebula, a place where new stars and planets can form.
Flickr/cafuego, CC BY-SA

By Aris Tritsis, Australian National University

We know that the birthplaces of stars are large molecular clouds of gas and dust found in space.

But what exactly determines the number and kind of stars and planets that are formed in these clouds? How was our Solar system nursed and how did it emerge from such a cloud billions of year ago?

These are mysteries that have been puzzling astronomers for decades, but research published today in Science adds an extra dimension to our understanding.

A 3D approach

Knowledge of the 3-dimensional structure of these clouds would be an important leap in our understanding of how stars and planets are born.




Read more:
From pancakes to soccer balls, new study shows how galaxies change shape as they age


The physics responsible for the formation of stars is also responsible for shaping the clouds. But even with the most advanced telescopes in the world we can only see the two-dimensional projections of clouds on the plane of the sky.

Thankfully, there is a way around this problem. A recently discovered type of structure in molecular clouds, called striations, was found to form because of waves.

Here enters Musca, a molecular cloud that “sings”. Musca is an isolated cloud in the Southern sky, below the Southern Cross, that looks like a thin needle (see top image). It is hundreds of light years away and stretches about 27 light years across, with a depth of about 20 light years and width up to a fraction of a light year.

Musca is surrounded by ordered hair-like striations produced by trapped waves of gas and dust caused by the global vibrations of the cloud.

3D model of Musca molecular cloud.
Aris Tritsis, ANU, Author provided

Trapped waves act like a fingerprint – they are unique and can be used to identify the sizes of the boundaries that trapped them. Boundaries are naturally created at the edges of clouds where their physical properties change abruptly.

Just like a cello and a violin make very distinct sounds, clouds with different sizes and structures will vibrate in very different manners – they will “sing” different “songs”.

A ‘song’ in the cloud

By using this concept and calculating the frequencies seen in observations of Musca it was possible to measure for the first time the third dimension of the cloud, the one that extends along our line of sight.

The frequencies found in the observations were scaled to the frequency range of human hearing to produce the “song of Musca”.

A “singing” molecular cloud.

The results from this method were amazing. Despite the fact that Musca looks like a thin cylinder from Earth, the true size of its hidden dimension is not small at all. In fact, it is comparable to its largest visible dimension on the plane of the sky.

No longer a thin cylinder when the extra dimension is revealed (Aris Tritsis)

Musca is not actively forming stars. It will be millions of years before gravity can overcome all opposing forces that support the cloud.




Read more:
Signals from a spectacular neutron star merger that made gravitational waves are slowly fading away


As a result, with its structure now determined, Musca can be used as a prototype laboratory against which we can compare our models and study the early stages of star formation.

The ConversationWe can use Musca to better constraint our numerical models and learn about our own Solar system. It could help solve many mysteries. For example, could the ices found in comets have formed in clouds rather than at a later time during the life of our solar system?

Aris Tritsis, Postdoctoral Fellow, Australian National University

This article was originally published on The Conversation. Read the original article.

When galaxies collide, size matters if you want to know the fate of our Milky Way

File 20180214 124893 hfpdt0.jpg?ixlib=rb 1.1
An artist’s impression of the predicted merger between our Milky Way (right) and the neighboring Andromeda galaxy (left). So which galaxy will dominate?
NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas; and A. Mellinger

Geraint Lewis, University of Sydney and Prajwal Kafle, University of Western Australia

Our Milky Way and the Andromeda galaxy – two giant galaxies in our local patch of the universe – are heading for an immense collision with each other in only a few billion years’ time. So which will dominate in this intergalactic tussle?

Our recent work has turned up an interesting result on measuring the mass of the Andromeda galaxy, which at a distance of only two million light years is our cosmic next-door neighbour.

Both Andromeda and the Milky Way appear to have about the same total mass, about 800 billion times that of our Sun, suggesting that the result of this intergalactic gravitational battle may actually be a draw.

In a few billion years, Andromeda and the Milky Way will merge. It is essential that we know their masses if we are to understand the details of this cosmic crash.



Read more:
Looking at the universe through very different ‘eyes’


Big brother, little brother?

The Andromeda and the Milky Way galaxies are very similar, giant spirals containing hundreds of billions of individual stars. But astronomers have struggled to work out which of these two galaxies is the most massive.

And knowing the masses of the two giant galaxies will help to reveal the details of our ultimate fate.

The answer to this question is vitally important if we are to understand the dynamic history of all nearby galaxies, both large and small, as the gravitational field of the most massive will command the action.

Until now, astronomers have been unable to pin down the galactic masses, with a lack of data and complex calculations yielding very uncertain answers.

At times it seemed that our own Milky Way was more massive; at others it appeared that Andromeda was the local Goliath.

In our Milky Way, where we can get the best observational data, there has been a growing consensus among astronomers as to its mass. For Andromeda, where observations are more difficult, astronomers have still struggled to measure an accurate mass.

Our new work takes a new approach to measuring the mass of the Andromeda galaxy.

A portion of the Andromeda galaxy (M31), our galactic next-door neighbour.
NASA, ESA, J. Dalcanton, B.F. Williams, and L.C. Johnson (University of Washington), the PHAT team, and R. Gendler

How to measure a galaxy?

Simply counting the number of stars in any galaxy, and adding their individual masses, won’t give you its total mass. Not even close. The mass of a galaxy is dominated by its dark side, an immense amount of matter that is unseen by telescopes.

The light side of a galaxy, the glowing stars and gas that we can see, accounts for only a couple of tens of percent of the total mass. The rest, the significant majority, is this elusive dark matter that dominates all of the mass in the universe.

But it is the gravitational pull of this dark matter that holds the stars in their orbits, meaning we can measure its presence. American astronomer Vera Rubin figured out more than half a century ago that there is much more to the Andromeda galaxy than simply the stars we can see.

As dark matter holds stars in their orbits, we can use their motions to measure the overall mass of the Andromeda galaxy, including the unseen dark matter. This is what we did in our new work, but with a twist.

Escape velocity is the key to measuring the mass of galaxies.
WikiHow, CC BY-NC-SA

The key concept is escape velocity, or how fast you have to be moving to break free from the gravitational pull of a massive object.

As Elon Musk and the Falcon Heavy rocket just showed, you need to get up to speeds of more than 11km per second to ensure that your Telsa electric car escapes Earth’s gravitational clutches.

We figured that if we can trace out the escape velocity for stars within the massive gravitational halo of Andromeda, we can work out its gravitational pull, and the mass that is ultimately responsible.

While the calculation was complicated, the result was unequivocal: previous estimates had overstated the total mass of Andromeda. It and the Milky Way are equals in the local universe.

Towards the future

Now we know that the Milky Way and Andromeda are of similar masses, what have we learned? Importantly, we can now try to understand the role these galaxies played in the formation and evolution of the local universe.




Read more:
The cosmic crime-scene hunt for clues on how galaxies are formed


But we know that the collision with Andromeda is coming in only a few billion years. Previously we were unsure who would be the major player in this battle, and who would dominate the gravitational battle ahead.

The ConversationLike the Mutually Assured Destruction (MAD) doctrine of the Cold War, ultimately there will be no winner in this cosmic clash, but at least the Milky Way will be on an equal footing with its cosmic rival.

Geraint Lewis, Professor of Astrophysics, University of Sydney and Prajwal Kafle, Postdoctoral research associate, University of Western Australia

This article was originally published on The Conversation. Read the original article.

Look up! Your guide to some of the best meteor showers for 2018

 

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The 2017 Geminids as seen from Ecuador, against the backdrop of the splendid Milky Way (centre) and the Large Magellanic Cloud (right).
Flickr/David Meyer, CC BY-NC-ND

Jonti Horner, University of Southern Queensland and Tanya Hill, Museums Victoria

This year gets off to a relatively slow start when it comes to seeing the annual major meteor showers.

The Quadrantids, one of the big three annual showers, are lost to the vagaries of the full Moon in early January.

But the year’s other two most active annual showers – the Perseids (in August) and Geminids (in December) – are set to put on fine displays.

So when and where should you look to have the best chance of seeing nature’s fireworks?

Here we present the likely meteoric highlights of 2018. These are the meteor showers most likely to put on a good show this year.


Read more: Stars that vary in brightness shine in the oral traditions of Aboriginal Australians


For each shower, we give the forecast activity period and the predicted time of maximum. We also provide charts showing you where to look, and give the peak rates that could be seen under perfect conditions (known as the maximum Zenithal Hourly Rate, or ZHR).

The actual rate you see will always be lower than this value – but the higher a shower’s radiant in the sky and the darker the conditions, the closer the observed rate will get to this ideal value.

To see the best rates it is well worth trying to find a good dark site, far from street lights. Once outside, make sure to give your eyes plenty of time to adapt to the darkness (at least half an hour).

Showers that can only be seen from one hemisphere are denoted by either [N] or [S], with those that can be seen globally marked as [N/S].

Lyrids [N/S; N favoured]

Active: April 14-30

Maximum: April 22, 6pm UT = April 23, 2am AWST (WA) = 4am AEST (QLD/NSW/ACT/Vic/Tas)

ZHR: 18+

Parent: Comet C/1861 G1 (Thatcher)

The Lyrids hold the record for the shower with the longest recorded history, having been observed since at least 687BC.

That longevity is linked to the orbit of the Lyrid’s parent comet, discovered in 1861 by A. E. Thatcher. Comet Thatcher moves on a highly inclined, eccentric orbit, swinging through the inner Solar system every 415 years or so. Its most recent approach to Earth was in 1861.

Compared with many other comets, Thatcher’s orbit is relatively stable, as the only planet with which it can experience close encounters is Earth. This means the meteors it sheds continue to follow roughly the same orbit.

Over the millennia, that shed debris has spread all around the comet’s vast orbit, meaning that for thousands of years, every time Earth intersects Comet Thatcher’s orbit, the Lyrids have been seen, as regular as clockwork.

One study of the orbits of Lyrid meteors even suggests the shower may have been active for at least a million years.

Across Australia, the Lyrids are best seen an hour before sunrise, when the radiant is at its highest [Brisbane 5am].
Museums Victoria/stellarium

These days, the Lyrids are usually a moderately active shower, producing somewhere between 10 and 20 fast, bright meteors per hour at their peak. Occasionally, though, the Lyrids have thrown up a surprise, with rates climbing far higher for a period of several hours.

The best of those outbursts seem to occur every 60 years or so, with the most recent occurring in 1982 when observed rates reached or exceeded 90 per hour.

No such outburst is predicted for 2018, but even in quiet years, the Lyrids are still a fun shower to observe.

From the USA, the radiant is well placed from late evening until early morning [Chicago 11pm].
Museums Victoria/stellarium

They are best seen from northern latitudes, but their radiant is far enough south for observers throughout Australia to observe them in the hours before dawn.

For observers at mid-northern latitudes, the Lyrid radiant reaches suitable altitude by about 11pm local time. Viewers in the southern hemisphere have to wait until the early hours of the morning before reasonable rates can be observed.

The forecast time of maximum this year favours observers in Australia and east Asia but the timing of maximum has been known to vary somewhat, so observers around the globe will likely be keeping their eyes peeled, just in case!

Perseids [N]

Active: July 17 – August 24

Maximum: August 12, 8pm UT – August 13, 8am UT = from August 12, 9pm BST (UK) = 10pm CEST (Europe) = 6pm EDT (East Coast, US) = 3pm PDT (West Coast, US) for 12 hours

ZHR: 110

Parent: Comet 109P/Swift-Tuttle

For observers in the northern hemisphere, the Perseids are a spectacular summer highlight. At their peak, rates often reach or exceed 100 meteors per hour, and they are famed for their frequent spectacular fireballs.

The Perseids are probably the best known and most widely observed of all modern meteor showers. They are remarkably consistent, with peak rates usually visible for a couple of evenings, and fall in the middle of the northern hemisphere summer holiday season. The warm nights and frequent clear skies at that time of year make the shower a real favourite!

Like the Lyrids, the Perseids have a long and storied history, having been observed for at least 2,000 years. Their parent comet, 109P/Swift-Tuttle, is a behemoth, with the largest nucleus of the known periodic comets – some 26km in diameter.

It has likely moved on its current orbit for tens of thousands of years, all the time laying down the debris that gives us our annual Perseid extravaganza. It will next swing past Earth in 2126 when it will be a spectacular naked eye object.

From the UK, the Perseids radiant is visible all night and summer is the perfect time for meteor watching [Greenwich 9pm].
Museums Victoria/stellarium

This year the forecast maximum for the Perseids favours observers in Europe, although given the length of peak activity, any location in the northern hemisphere has the potential to see a spectacular show on the night of August 12.

But don’t despair if it’s cloudy that night, as the Perseids have a relatively broad period of peak activity, meaning that good rates can be seen for a few days either side of their peak.

In 2018, the peak of the Perseid shower coincides with the New Moon, and so is totally unaffected by moonlight, which makes this an ideal year to observe the shower.

The further north you are, the earlier the shower’s radiant will be visible. But reasonable rates can typically be seen any time after about 10pm, local time. The later in the night you observe, the better the rates will be, as the radiant climbs higher into the sky.

It is not uncommon for enthusiastic observers to watch the shower until dawn on the night of maximum, seeing several hundred meteors in a single night.

A fantastic Perseids display from 2016 over Austria.
Flickr/Michael Karrer, CC BY-NC

Draconids [N]

Active: October 6-10

Maximum: October 9, 12:10am UT = 1:10am BST (UK) = 2:10am CEST (Europe)

ZHR: 10+

Parent: Comet 21P/Giacobini-Zinner

The Draconids are a fascinating meteor shower, although in most years, somewhat underwhelming. Unlike the previous showers, the Draconids are a relatively young meteor shower that can vary dramatically from one year to the next.

First observed less than a century ago, the Draconids (also known as the Giaocobinids) are tied to a Jupiter-family comet called 21P/Giacobini-Zinner.

That comet was the first to be visited by a spacecraft, and has frequent close encounters with Jupiter, which continually nudges its orbit around. These encounters also perturb the meteor stream the comet is laying down, sometimes enhancing rates at Earth and sometimes diminishing them.

In the early 20th century, it was realised that Comet Giacobini-Zinner’s orbit comes close enough to Earth that we might be able to see meteors as we plough through the debris it leaves behind.

This led to the first predictions of Draconid activity. Sure enough, in 1920, the great meteor observer W. F. Denning confirmed the existence of the shower, with a mere five meteors observed between October 6 and October 9.

In 1933 and 1946, the Draconids produced two of the greatest meteor displays of the 20th century – great storms, with peak rates of several thousand meteors per hour. In those years, Earth crossed the comet’s orbit just a month or two after the comet passed through perihelion (closest approach to the Sun), and Earth ploughed through dense material in the comet’s wake.

After 1946, the Draconids went quiet, all but vanishing from our skies. Jupiter had swung the comet onto a less favourable orbit. Only a few Draconids were seen in 1972, then again in 1985 and 1998.

The late 1990s saw a renaissance in our ability to predict and understand meteor showers, born of enhanced activity exhibited by the Leonid meteor shower. Using the techniques developed to study the Leonids, astronomers predicted enhanced activity from the Draconids in 2011, and the predicted outburst duly occurred, with rates of around 300 meteors per hour being observed.

Europe is well placed to catch some Draconids streaming from the eye of the dragon, near the star Rastaban [Paris 12:30am].
Museums Victoria/stellarium

This year comet Giacobini-Zinner once again passes through perihelion and swings close to Earth’s orbit. The chances are good that the shower will be active – albeit unlikely to produce a spectacular storm.

Modelling suggests that rates of 20 to 50 faint meteors per hour might be seen around 12:14am UT on October 9. Other models suggest that rates will peak about 45 minutes earlier, with lower rates of 15 to 20.

The Draconid radiant is circumpolar (that is, it never sets) for locations north of 44°N, and is highest in the sky before midnight. This year, the Moon is new at the time of the forecast peak, which is ideally timed for observers in Europe.

If skies are clear that evening, it is well worth heading out at around 11:30pm BST on October 8 (12:30am CEST on October 9) and spending a couple of hours staring north, just in case the Draconids put on another spectacular show.

Taurids [N/S]

Active: September 10 – December 10

Maxima: October 10 (Southern Taurids); November 12 (Northern Taurids)

ZHR: 5 + 5

Parent: Comet 2P/Encke

Of all the year’s meteor showers, the one that dumps the greatest amount of dust into Earth’s atmosphere are the Taurids. The inner Solar system contains a vast swathe of debris known as the Taurid stream. It is so spread out that Earth spends a quarter of the year passing through it.

In June, that debris spawns the Daytime Taurid meteor shower, which (as the name suggests) occurs during daylight hours, and is only really known thanks to radio observations.

After leaving the stream for a little while, Earth penetrates it again at the start of September, and activity continues right through until December. Hourly rates fluctuate up and down, with several distinct peaks and troughs through October and November.

The Taurid stream is complex – with at least two main components, known as the northern and southern branches. Typically, the Southern Taurids are active a little earlier in the year and reach their peak about a month before the northern branch.

During northern autumn, the Taurids can be seen radiating from the western sky before dawn [Paris 6:30am October 10].
Museums Victoria/stellarium
For the southern spring, the Taurids radiate from the northern sky before dawn [Melbourne 3:30am November 12].
Museums Victoria/stellarium

The Taurids are slow meteors and feature plenty of bright fireballs. So even though their rates are low, they are well worth looking out for, particularly when other showers are also active, such as the Draconids, the Orionids and the Leonids.

Put together, these showers make the northern autumn or the southern spring a great time to get out and look for natural fireworks.

Orionids [N/S]

Active: October 2 – November 7

Maximum: October 21

ZHR: 20+

Parent: Comet 1P/Halley

Twice a year, Earth runs through the stream of debris littered around the orbit of Comet 1P/Halley. Throughout the month of October this gives rise to the Orionid meteor shower.

The Orionids are a fairly reliable meteor shower with a long, broad maximum. Typically, peak rates can last for almost a week, centred on the nominal maximum date. Throughout that week, Orionid rates can fluctuate markedly, leading to a number of distinct maxima and minima.

Orionid meteors are fast – much faster than the Taurids that are active at the same of year. Like the Taurids, they are often bright, the result of the high speed at which the meteoroids hit Earth’s atmosphere.

Before sunrise, Orion stands upright in the southwest as seen from the northern hemisphere [Chicago 5am].
Museums Victoria/stellarium
But from the southern hemisphere Orion appears to be standing on his head, in the northern sky before dawn [Sydney 5am].
Museums Victoria/stellarium

The Orionid radiant rises in the late evening and is only really high enough in the sky for reasonable rates to be seen after midnight. As a result, the best rates are usually observed in the hours before dawn.

This works well this year, as the Moon will be in its waxing gibbous phase, setting some time after midnight and leaving the sky dark, allowing us to watch for pieces of the most famous comet of them all.

Geminids [N/S]

Active: December 4-17

Maximum: December 14, 12:30pm UT = Australia: December 14, 8pm AWST (WA) = 10:30pm (QLD) = 11:30pm AEST (NSW/ACT/Vic/Tas) = United States: December 14, 7:30am (EST) = 5:30am (PST) = 2:30am (Hawaii)

ZHR: 120

Parent: Asteroid 3200 Phaethon

As the year comes to a close, we reach the most reliable and spectacular of the annual meteor showers – the Geminids. Unlike the Perseids and the Lyrids, which have graced our skies for thousands of years, the Geminids are a relatively new phenomenon.

They were first observed just 150 years ago, and through the first part of the 20th century were a relatively minor shower. But since then rates have improved decade-on-decade, to the point where they are now the best of the annual showers, bar none.

The reason for their rapid evolution is that their orbit (and that of their parent body, the asteroid Phaethon) is shifting rapidly over time, precessing around the Sun (wobbling like a slow spinning top). As it does so, the centre of Phaethon’s orbit, and the centre of the Geminid stream, are moving ever closer to Earth.

For northern locations, the radiant rises shortly after sunset, and good rates can be seen from mid-evening onwards. For observers in the southern hemisphere, the radiant rises later, so good rates are delayed until later at night (as detailed in our 2015 report on the shower).

Although the time of maximum this year seems to favour observers in the Americas and Australia, peak rates from the Geminids usually last around 24 hours, and so good rates should be visible around the globe.

This year the maximum falls a day before the Moon reaches first quarter so the best rates are visible (after midnight, local time) when the Moon will have set and moonlight will not interfere.

Australia’s summer meteor shower, the consistent and spectacular Geminids in the early morning sky [Brisbane 4am].
Museums Victoria/stellarium
The Geminids appear high overhead over American skies in winter [Los Angeles midnight].
Museums Victoria/stellarium

Given that rates from the Geminids continue to climb, the estimated ZHR of 120 is likely to be somewhat conservative. Rates in excess of 130, and even as high as 200 per hour, have been seen in recent years.

Geminids are medium-speed meteors and are often bright. The individual meteors also seem to last just that bit longer than other showers, a fact likely related to their parent object’s rocky nature.

The ConversationWherever you are on the planet, the Geminids are a fantastic way to bring the year to an end, and we will hopefully be treated to a magnificent display this year.

Jonti Horner, Vice Chancellor’s Senior Research Fellow, University of Southern Queensland and Tanya Hill, Honorary Fellow of the University of Melbourne and Senior Curator (Astronomy), Museums Victoria

This article was originally published on The Conversation. Read the original article.