Answers for authors: What is the view like from different parts of our galaxy? (re-posted)

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The Space Foundation

To answer this we first need a quick bit of galactic geography:
Go out on a really dark, clear, night, far from any artificial lights, give your eyes time to adapt to the darkness, and look up. You will probably see many more stars than you’re used to and, stretching across the sky from horizon to horizon, a long band of faintly lowing fuzziness: That's the Milky Way, the galaxy that our Sun, our solar system, and this planet are part of.
 

This thing - although this is a long exposure that intensifies the light in the image. It doesn't look much like a swirl of stars from Earth, as we're inside the disk

It’s a collection of hundreds of billions of stars, at least that many planets, comets, nebula, and much weirder things with names like ‘magnetars’, ‘pulsars’, ‘white dwarfs’ that sound like they came straight out of an early draft of superhero comic. It's actually shaped like the swirl of cream in a coffee mug - and we can divide it into three bits:

• The central bulge / galactic core: The centre of the swirl, the core is made of a mix of stars of all ages. It's also one of the oldest neighbourhoods, and has both a lot of old stars and clusters of very young stars, and gas clouds primed for new star growth. Everything is very close packed (less than half a light year between stars on average, often much closer). The bulge is about 5,000 light years in radius, and has at least two gigantic black holes in the centre, one of which is the supermassive Sagittarius A* black hole, our galaxy's central black hole which weighs as much as 4,300,000 Suns. 
• The disc/arms: The arms of the swirl. About 60,000 light years in radius, and around 1,000 light years deep where the Sun is, it's mainly made of young to middle age stars. Beyond the edge of the disk is a mysterious ring of stars and gas surrounding it, with a radius of 75,000 to 80,000 light years, called the Monocerous ring. 
• The galactic halo: This is where my coffee metaphor runs out completely, unless you’ve brewed your coffee in weightlessness and then spilled it – these are, well, wispy bits outside the main galaxy. They are made of widely spaced gas and stars, floating above or below the plane of the disk in a rough ball, stretching to a radius of 130,000 lightyears. Although the stars and gas are incredibly sparse there, set within the halo are locales called globular clusters: Round clusters of hundreds of thousands of ancient stars, which are often separated from each by less than the width of our solar system.

Let’s assume I’ve got a ship fast enough, and well supplied enough, to go around the galaxy and stop in each section. What would my human eye see? 

The galactic disk: 

A map of the galactic disk, showing the spiral arms. Courtesy of Universe Today.

The nice thing about figuring out the view from the galactic disk is I live in it: Earth is located in the 'Orion spur' - a sub arm of the disk about 25,000 light years from the galactic centre. So there's lots of information to go on...

After my eyes have some time to adjust to the darkness the Milky way is a rough, very broad, band of faintly glowing fuzz stretching across the sky. In the direction of the constellation Sagittarius I can see a bulge in the band, with dark gaps in it - that's the direction of the galactic core. The gaps are dark nebula, blocking light from that direction out. 
I can't actually see the galactic core - there's too much gas, dust,and intervening stars in the way. What I see is the result of the disk getting slightly thicker in that direction.
If I look about with care I see the occasional dim fuzzy blob of a star forming nebula (like the one on Orion’s belt), and glittering collections of blue stars - open clusters. 

Above: The Pleiades, a cluster of young stars still wearing the remains of the nebula that created them.

The stunning colours I've seen in pictures from space telescopes are nowhere to be seen because, well, my eye isn't a space telescope. But it's good enough to make out some things: Above and below the plane of the galaxy I can see the Magellanic Clouds - smaller galaxies that orbit the Milky Way - as broader fuzzy patches well away from the galactic centre.


The galactic centre: 

Above: Incredibly densely clustered stars near the galactic core, Courtesy of the European Southern Observatory.

The stars of the core are densely packed, often living within fractions of a light year of each other, and many of the biggest and brightest are either huge, ancient, red stars or clusters of equally bright, young blue ones. The bright, close clustered, stars around me stop anything outside the galactic centre being  visible - the core seems to be the whole universe.

The sky is much, much brighter than on Earth: A lot of these stars are as bright as Venus from Earth – some are as bright as a full moon all by themselves. How bright is that in total? It’s very had to tell exactly, because clouds of gas and dust keep us from getting a really good count and the brightest stars wash out the fainter ones… but a back of the envelope calculation suggests the sky would glow with at least 1/300 the the brightness of the Sun from Earth**.

If that doesn’t sound so bright – the full Moon is juist 1/400,000 the as bright as the Sun, so the sky in the galactic core would be over a thousand times brighter than the full moon. Switching the lights off on my spaceship would still leave me with the equivalent light of bright sunset.

But!

If I head deeper into the core, eventually I come to the heart of darkness: Sagittarius A*, the 4.3 million solar mass black hole our galaxy is centred on. The vast black hole is 'only' as wide across as the orbit of the planet Mercury, but for half a lightyear around it is a swirling doughnut of superhot gas that X-ray telescopes can pick up even from Earth -
the graveyard of stars and planets that passed too close to the hole.

The galactic halo: 

Above: The Andromeda galaxy, in a long exposure photograph that brings out otherwise invisible details. Our galaxy might look similar, from outside. Courtesy of Brian Snyder.

The galactic halo is pretty lonely place. I’m well outside the galactic bulge and the disk, which are stretched out below me. 

I might have expected to see something like a celestial fried egg in an infinite black frying pan - but then I’m not remembering the view from Earth: There the galaxy is a dim fuzzy band across the night sky, even though I was looking lengthwise through it, with all the accumulated light of the  galaxy on my line of sight. Up here, looking down on the relatively thin galactic disk from a great distance, the only part that is very bright to the human eye is the galactic central bulge: A twinkling, fuzzy edged, blob of a billion stars – from here it’s easily brighter than the full Moon. 

Around it is an ethereal, almost invisible swirl of mist. That’s the galactic disk. You don’t need to take my word that it would be virtually see through: The Andromeda galaxy, that is regularly in the night sky from most locations, and it’s bigger than a full Moon. 

Ever seen it hanging in the sky? 

Above: The Andromeda galaxy, in a long exposure shot that makes it's outer regions brighter, and easier to see. Courtesy of Ted Van.

Probably not – even through a telescope, the only really visible bit is it’s galactic core. The spiral arms are vast, but too thin for our eyes to really make out.  

That said, it’s a dark sky out here: Rather than being separated by five or six light years, as in the spiral arms, the stars out here are separated by hundreds or thousands of light years. For that reason, if you turn so the bright core is behind you, it’s possible to dimly make out the structure of the spiral arms. Other galaxies are also more visible than from Earth, even through the disk of the Milky Way.

Globular cluster: 

A globular cluster - a vast ball of ancient, close packed stars.

 The last stop on our galactic whistle stop tour: These are huge collections of ancient, red stars floating in the galactic halo. Mostly they're located in a shell around the galactic core - and the stars are, if anything, even more tightly packed – big, bright old stars, dating from when the rest of the galaxy was just a huge cloud of gas. I can't see much outside of the cluster, except maybe the galactic core. 
Although this place is as bright as the core, the quality of the light is different: Orange-white, as every star is an ancient red giant or dwarf.
The close stellar quarters means that any planets will have been stripped away from their solar systems - not that there will have been many: Globular clusters are incredibly poor in heavier, planet forming, elements. This is a place where no new stars have been formed for billions of years - in many ways it's a tiny, zombie galaxy in it's own right.

And, finally, I can turn and head back to Earth. Hopefully I didn't leave the oven on... 

**The back-of-an-envelope calculation went: The very central cubic parsec (1 parsec = 3.26 lightyears) of our galaxy is estimated to contain 10,000,000 stars. To get a rough lower limit for how bright that would be, lets assume all those stars are as bright as the Sun (in reality many of them are far, far brighter), and arrange them in a sphere with a radius of 0.825 light years - the average distance from the centre assuming the stars are evenly spaced. Earth is 8 light minutes – 0.000015 of a light year, from the Sun. That means our hypothetical stars are each 55000 times further away from the centre of the sphere than the Sun is from Earth. Luminous intensity decreases with the square of distance, so each of those stars is delivering 1/ 3,025,000,000th of the Sun’s intensity at Earth. Multiplied by 10,000,000 that givs a total brightness, across the whole sky, of 1/302th the brightness of the Sun from Earth. 

Answers for Authors: What would life be like on a planet orbiting a red dwarf star? (re-posted)

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The Space Foundation

A tiny star 40 light years from Earth, called TRAPPIST-1*, made some major waves a while back: It has seven planets, all roughly the same size as Earth, all with some chance of habitable conditions.

Above: An artists impression of the TRAPPIST-1 solar system.

So the question has been asked: If a civilisation were located on one of the TRAPPIST-1 planets, what would be different to our civilisation?

Short answer? A lot. 

Long answer?
First lets look at the TRAPPIST-1 star itself. It's an ultra cool red dwarf, the smallest kind of true star** you can get - just 8% the Sun's mass, and barely wider than our planet Jupiter. That gives it a very different look to our Sun: In a nearby planet's sky it would appear orange coloured, and dimmer. Paradoxically, if you're viewing from a habitable world, it would also look slightly bigger as a red dwaf's habitable zone is much closer in than  our Sun's. Red dwarfs also suffer from huge star spots, giving it a mottled look - and these come as part of a package stellar violence: TRAPPIST-1 spits out powerful particle storms, and a lot of UV and X-ray radiation.  Although invisible except to specialised instruments, coronal mass ejection particle storms (responsible for auroras on Earth) damage the electronics of satellites and spacecraft, cause cancers in astronauts, and cause radio blackouts and damaging power surges here on Earth. Those from TRAPPIST-1 would hit its planets like the strongest storms ever spat out by our Sun.

But being dim, orange, angry, and ugly is no obstacle to success - look at Donald Trump. Being so small means TRAPPIST 1 burns its nuclear fuel much more slowly and efficiently than our sun, so it will live thousands of times longer.  

I truly hope the Trump doesn't live thousands of times longer than expected . Though he is full of surprises... horribly full of them...

So that's TRAPPIST-1 itself: Small, orange, angry, and tenacious. What about the planets around it? 

There are seven of them and, because such a small star only has small gravity, they must orbit much closer than any of our planets to stay bound.  The furthest of them still has an orbit much smaller than Mercury's. But the cool stars small size means these worlds don't scorch - that outermost world is probably an ice ball! The habitable zone, where planets are most likely to have liquid water, is closer still - three of the planets are in it. 

So, making the assumption that any civilisation will be based on one of the habitable zone planets, we can come to a few conclusions: 

• The Sun will look orange, bigger in the sky than ours, and dimmer to look at. There aurora will be spectacular - assuming the planet has a strong protective magnetic field. 
• If the planet doesn't... the very powerful, close range, solar storms will have damaged and thinned the atmosphere, leaving it more like a big version if Mars than Earth.  
• The year will be a couple of weeks long at the most - if the planet has seasons each would only last a couple of days. 
• These planet's close range to their sun might make them 'tidally locked' - so one side  always faces the sun, and one side always faces away. That would make the sun stand still in the sky, bathing half the planet in eternal day, and the other half in eternal night. A thick atmosphere  will balance the extreme temperature  differences out a bit, but one side would still be a place of bitter cold and ice caps,the other a realm of deserts.  Only a strip of the planet along the day/night boundary would be temperate,  limiting the civilisation's ability to spread. 
• Because of this solar system's  small size the other planets would look much bigger in the sky than the planets of our solar system - often bigger than the moon from Earth. So if more than one planet had a civilisation each could see the glow of each other's city lights at night. 
• Plantlife would be a different colour from Earth's: Our plants are green, because that's the brightest colour in the Sun's spectrum (see 'what colour is the Sun'), and the plants need to reflect the brightest light to avoid cell damage. But a red dwarf's light is fainter, so plants on a TRAPPIST 1 planet might well be black, to absorb as much as possible .
•  The sky would also be a different: Our sky is blue thanks to scattered blue light from the Sun, which TRAPPIST 1 produces less of - so it's sky would be much darker. Since the blue wavelengths  are absent the sky might even be green, as that colour is the more abundant wavelength short enough to scatter off air molecules.

What about travel between those planets? The orbits of these worlds are the same sort of distance apart as the Earth and Moon (which are only three days travel apart using 1960's rocket technology).  Because the orbits are so short launch windows would occur on a weekly basis... Which makes the TRAPPIST 1 solar system sounds like an ideal place for a spacefaring civilisation.

It's not that we're complaining about how hard space travel is universe... well... actually it is.

But this teeny star system also has hazards - the planets will need heavy duty magnetic fields to protect them from their ill tempered sun,  and some radiation will get through anyway.  A surface civilisation will need to be very X-ray tolerant. On top of that, the closeness of the planets means they tug on each other gravitationally, changing each other's orbits over millennia and causing huge climate shifts.

So, to sum up? A civilisation around TRAPPIST 1 would be able to travel between the worlds there in days, and their seasons would race past in mere days. The plants would be orange (assuming they worked the same way as ours), and the sun would be distinctly orange in the dark sky, and would look larger than ours, and the other worlds would loom in the sky, as big as the Moon looks from Earth. But they will need to be hardy: Only thin strips of their worlds, along the terminators, would be habitable - the rest of their surfaces will be gripped in eternal roasting day or endless freezing night. Radiation levels will be high, with frequent  solar storms powerful enough to cause worldwide radio blackouts, power grid surges, a severely damage satellites. Humans would face elevated cancer risk, even on the ground, and in space a storm could be lethal.

A fascinating setting - but not for the fainthearted...

*Named after the beer brewed by Trappist monks . NAMED AFTER BEER! 
*A true star fuses hydrogen for fuel. Objects much smaller than TRAPPIST-1 can only fuse deuterium, and are called 'Brown dwarfs'.

Answers for Authors: Where should I site my galactic civilisation (re-posted)?

Learn the ins and outs of pseudoscience, and debunking it: Read 'Escaping The Rabbit Hole' here.

Want to support the future science and engineering? You can do so through one of these charities:

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The Space Foundation

It's good to be Emperor...

You need an evil galactic empire, or a benevolent  planetary federation, to set your scorching page turner of space opera in. The problem is that, to help your readers suspend their disbelief, you now have to figure out a believable interstellar civilisation. And write it a plausible sounding history. With a way of being founded and of expanding that makes sense. And you can't look that stuff up with Google...

....weeeeell.... actually... 

I've spent far too much time reading papers and sitting courses on the search for extraterrestrial intelligences, so I know a surprising fact: Some very, very, clever brains (they include Stephen Hawking and Carl Sagan) have devoted serious man hours to what a huge galactic civilisation could be like. Not for fiction, but because they think we should be checking the sky in case there really is one somewhere.

That means there's a lot of stuff been written that can help you. Much more than a blog posts worth (I'll have to write a book... hmmm) so here I'll just try and sum up their thoughts on most important aspect, re-mixed for SciFi instead of SETI. And that big important aspect is, of course: Location, location, location.

It’s very much like looking for a house – you need to think about location, access to amenities, commuting, and what won’t break your budget. Admittedly the plumbing is rather more complicated on an interstellar empire. And the call-out fees are a nightmare if it breaks...

"Suitable for a buyer who really likes space... ahahaha..." Never trust an estate agent nicknamed 'Slick' guys.

In much the same way that it’s only a truly exceptional house that doesn’t need the ground*, unless your empire builders can wave away fundamental laws of physics** you’ll at least need your location to fill some basic needs:

• It will need an energy source. This probably means stars, but other energy sources – like the matter falling into a super massive black hole or the radiation beams of a pulsar, do exist. There is even a scale - the Kardashev scale - for rating any alien empires by how much power they use.
• It will need planets, or at the very least the kind of heavy elements planets are made out of  as building materials for artificial living structures like ringworlds.
• It doesn’t have to be friendly to life – your empire builders could have migrated there from a more hospitable part of the universe when they had the technology to handle the difficult conditions – but it needs to be close enough to at least one friendly environment for someone to have made the trip.

Then there are other things that it’s very useful to have, but a lack (or overabundance) of which could be overcome to a greater or lesser extent using technology or good planning:

• Commuting: You’ll probably want your empire to be small enough to get messages across in a reasonable time. Many authors do this by introducing a Faster Than Lightspeed (FTL) drive - although other methods, such as much longer than human-normal lifespans (via gene engineering or suspended animation), are also thrown about by both authors and scientists. But another way, if you’re not committed to an Earth centred civilisation, is to just set your empire in a part of the universe where the distances between stars are smaller than the five light years that the stars near Earth average (see below). If George Lucas can have a galaxy far, far away then why not you...?
• Stable environment: In the same way at you wouldn’t buy a house in the part of town where gangs occasionally leave heads in dustbins (although I once rented such a place), you wouldn’t set up a civilisation in a part of the galaxy where there are good odds that radiation from a supernova, neutron star collision, or belch from a supermassive black hole might fry it to a crisp. True, you could overcome this with technology, but let me assure you: No house alarm is truly unbeatable, and I expect that so no technological solution to stellar dangers will be either.
• Minimum age requirement: This goes hand in hand with the need for a quiet neighbourhood – young areas of the galaxy, like young clusters and star forming nebula, tend to be crowded with troublemakers like unstable blue giant stars, dense molecular clouds, and wandering black holes. Older locales tend to be much quieter, since the dangerous stars tend to have blown up or burnt out eons back. Older locales also have had more time to spawn native life forms who can rebel against (or ally with) your empire.
• Conditions suitable for life (of some kind) to arise: Not an absolute need - a sterile locale could be colonised from outside. Still, it’s simpler in terms of backstory for a thriving civilisation to grow up near to the planets that spawned them, and that means they need a few things: A stable environment, a ready supply of chemical energy, some form of chemistry complex enough to support things like DNA, and some way of mixing everything together – usually a good solvent like water – are generally regarded as the minimum. You can waive at least some of them, however, if you make your life form exotic : A.I, sentient gas clouds, energy based, or whatever your imagination can conjure.
• Life forms suitable to reach technological era: NASA and ESA are spending a lot of money looking for evidence of bacterial life on Mars, but it’s unlikely bacteria are going to build stargates or leave their home planet by anything other than accident^* . Hence you need creatures that could invent and use technology. 

Above: The stunning colours (which a human eye would never actually see) of a star forming nebula. A beautiful sight, but a very dangerous place to live.

Just based on those we can rule out some locations already: The great voids between galaxies would be impossible to build in without importing massive amounts of both matter and energy across billions of light years. Some galaxies have stars that are much further apart than normal, so trips would take longer and they would be scarce of energy and building material too. The same applies to the galactic halo, and intergalactic space. Active galaxies, where massive black holes are sucking down matter and belching back out radiation, are hard places for life to ever arise in or anywhere near. 

Above: The Andromeda galaxy - nice a roomy, lots of close packed stars, and private parking.

If you’re not employing FTL engines, or if they’re limited to some practical upper limit, you probably want some improvement on the years long travel times needed for even light to reach the nearest stars to Earth -  so the Milky Way's galactic core is attractive with its close packed solar systems, but the risk of supernova, neutron star collisions, and giant black holes make it much less attractive long-term. Something similar applies to young clusters of new formed stars, or active star forming nebula.


But there are good locations to be found - here are a few suggestions: 

• A multiple star system. The Universe abounds with stars and solar systems that are bound in small clusters by gravity, orbiting about each other. The individual stars are usually much less than a light year apart, often only light months or weeks, but there’s usually enough room between them for each star to have a habitable zone and fully developed system of planets. You could invent your own such star system - which is what the writers of the Battlestar Galactica remake did - for example: Four red dwarf stars with seven planets orbiting each star, might plausibly give you twelve habitable worlds (three in the habitable zone of each star) all packed into a light month of space^.  There would also be another sixteen uninhabitable but potentially mineable worlds. True, this is the entry level galactic empire - but it’s limited extent is compensated for with other advantages. In particular, if you want a real locale that is also close to Earth, then the nearest star system to Earth (the three star cluster of Proxima, Alpha, and Beta Centauri) actually fits the bill^^: Small by galactic standards, but still an empire greater than every civilisation of Earth combined.
• Globular clusters:  These collections of hundreds of thousands of stars have a lot to recommend them – they’re old, so there are few or no dangerous, radiation spitting, potentially explode-ey young stars around. Instead most of the stellar population are red dwarfs, with their tight wound systems of planets, or red giants destined to die relatively quiet deaths. Average distance between stars is down to less than three light months – so even a sub-light speed starship could cross between several star systems over the course of a year. On the downside: Planets orbiting any Sun-like stars would be pulled out of orbit by neighbouring stars, and Globular clusters are generally quite poor in heavy, planet building elements, so only fairly small planets (like Earth) would form around their stars. But these aren't showstoppers: Planets orbiting red dwarf stars would be much more likely to stay with their suns (there's an interesting Harvard study on it here), as these hug their planets much closer, and some of these clusters do have enough planet forming elements. On top of that the age of these stars - 5 billion years at least -  makes it more likely for a technological civilisation to have had time to arise^°. Globular clusters are not without hazards to navigation However: The long dead blue super stars, the absence of which makes the cluster fairly quite, will have left behind things like black holes and pulsars, which will be concentrated in the core. 
• Open clusters: Open clusters, on the whole, are not great spots for civilisation building - most open clusters are both too young for any worlds to have given rise to complex life, and are filled with big, radiation spitting, supernova prone, blue stars. Older ones, where things have settled down, are rare – the members of open clusters are usually born with enough speed to escape the cluster, so they drift apart in a few tens of millions of years. But some of the biggest have got enough gravity to have stayed together for hundreds of millions, or even billions, of years. Examples are places like the Beehive cluster, which is coming up on 3/4 of a billion years old, and is composed mainly of red dwarfs and sunlike stars. Near the clusters core these are packed within maybe as little as 1/2 a light ear of each other, and while these clusters may not be old enough time for technological life to arise (that took over 4 billion years on Earth), they have had time for a stable ecosystem to form that would support colonists. 
• Ultra compact dwarf galaxies. These are quite a new discovery, and something of a mystery – tiny galaxies less than 200 light years across, that are as jam packed as the cores of globular clusters. Like globular clusters they’re mainly made of older, redder, stars and many of the same things apply to them, but they have higher levels of planet building heavy elements. 
• Giant elliptical galaxies: For the big dawgs only – old and stable but up to 6,000,000 light years across, one of these could be home to a titanic empire of trillions of star systems – and is more likely to be so than the Milky Way ever will: The majority of stars in these galaxies are old, stable, and long lived - and there are trillions, so they have a good chance of having spawned a civilisation. But these are vast, vast places that could swallow our galaxy without noticing, so your empire builders better have mastered a powerful means of FTL travel, immortality, or both. 

These are just suggestions, but there are locations out there to fit most plot needs. The question is, simply, what kind of empire does your Imperial Majesty want? 

Above: The Voyager 2 probe encounters the planets of a red dwarf star.

*  Space stations, maybe, would count.

** You could write an empire like that: A civilisation so advanced it can more or less conjure matter and energy out of nothing, lurking in the utter darkness between the galaxies. Sounds like it might have some potential in a very Lovecraftian way, no? But a civilisation that advanced would be capable of almost anything, and so would suffer from the superman effect – it’s almost impossible to write a story for them because it’s impossible to think up a problem or obstacle they couldn’t solve almost instantly. If you don’t believe me I cite every superman film since superman 2 as evidence. 

^* There really are plausible ways bacteria might naturally leave their home planet and colonise another by accident, such as riding the debris from a giant asteroid strike, but you’d need to be writing a very esoteric story for that to count as an empire. Some kind of communal bacterial intelligence might work, but you’d have to have your heroes charge into battle against the evil empire by scrubbing every kitchen work surface on the planet with Dettol. 

^For hard SF writers: That means the furthaest worlds could be travelled between in five months with a starship that could hit 20% of lightspeed – a speed many researchers believe we could reach with engine designs we could build in the next century. A radio message could make the same journey in one month, giving a slightly better messaging time than existed between the furthest corners of the Roman empire.

^^Two sun like stars (alpha and beta centauri)about the same distance apart as the Sun and Saturn, with a red dwarf star (proxima centauri) orbiting the larger two at a distance of ¼ of a light year. There’s a confirmed planet in the habitable zone of the red dwarf, and a possible detection of one in a very tight orbit around one fo the Sun like stars. Small, undetected planets in the habitable zones of the sun like stars are possible. It’s very plausible to put a human colony around each of the stars, with the occupants able to visit each star system in less than a year with sub light speed engines. A small empire of three solar systems - but still bigger than every empire on Earth combined.

°^A civilisation taking in a whole such cluster would control hundreds of thousands of systems, but its inhabitents would need to be longer lived than modern humans, or have FTL – these clusters are often over a hundred light years in dimeter despite being so close packed. 

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Two new acheivements in private spaceflight...

The view over the engine bell of a SpaceX rocket, leaving Earth behind for the  GEO satellite belt.

Over the last fifteen years a lot of words associated with the fledgling private space flight industry have gone from being said almost in mockery to being said in earnest - even admiration. This week has seen two events that highlight why....

SpaceX has flown a flight proven booster, with a flight proven space capsule, to the International Space Station:

When Elon Musk's ground breaking 'SpaceX' (Space eXploration technologies) company announced they were planning to start re-using the first stage boosters from their rockets they were referred to as 'flight proven' - a euphemism for  'risky and unproven technology'.

Today that phrase 'flight-proven' is being used in earnest. And, to prove it, last week they flew not just a flight proven booster - but a flight proven booster carrying a flight-proven capsule, on a supply run to the international space station:

 

That's a milestone, because it makes SpaceX's vehicles mostly re-usable and therefore well positioned to bring the costs of spaceflight down. And, coming in the same week that Trump signed his (fairly vague) instructions for NASA to make a manned return to the Moon, it makes the upcoming decade look rather interesting for fans of manned space exploration....

Blue Origin flies 'Mannequin skywalker' to the edge of space:

Jeff Bezo's secretive company 'Blue Origin' has made impressive  progress in getting their 'New Shepherd' space vehicle ready to start ferrying passengers and missions to the edge of space. But a hydraulic malfunction on their first full tale test flight last year put a crimp in their plans. Now they've resumed  by flying a test dummy to the edge of space... a test dummy named Mannequin Skywalker.

No say anything about wanting to send Hayden Christensen into space.

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'Liquid' - in deep frozen interstellar ice.

The rings of Saturn, made of trillions of ciy particles loaded with organic matter - how far can chemical evolution get in such places? 

Life arose here on Earth... but how far did purely chemical evolution get towards life, on the planetoids and protoplanets of the early solar system? New research from Hokkaido University implies it might have been further than we thought. 

Meteorites dating from long before Earth have been found to contain the chemical components of proteins, cell walls, and even building blocks of DNA. Exactly how that happens is badly understood. We know these meteorites are fragments of ancient proto-worlds - worlds which were surprisingly planet like, with liquid water percolating through their rocks, planet like cores and volcanism, out gassing driving short lived atmospheres, and magnetic fields. They could have provided the right environments to process the more primitive chemistry in the Sun's protoplanetary disk.

But some meteorites contain relatively advanced pre-biotic chemistry despite showing no sign of ever having gotten above freezing. So where did it come from?

Now a surprising explanation has been discovered: Researchers from Hokkaido University in Japan have discovered that simple organic compounds, frozen in interstellar ice, start reacting with each other as if they are in a liquid, when exposed to ultraviolet light. The interstellar ice itself, despite being far below freezing, seems to behave like a super cold fluid - somehow. 

Above: Deep frozen, artificial, 'interstellar ice' bubbling like boiling water under UV light.

That's plenty of a mystery itself, but discovering that this kind of chemistry can take place in the ice grains floating in space (instead of a planetary environment) literally opens up a sky full of new possibilities: Across large parts of the universe worlds could be forming with half the chemical steps towards starting life already done.

Our skies might just have become a lot more crowded. For the original paper click here.

Did Earth just get buzzed by an alien starship?

 

If it was one of these then we're all in trouble.

To answer the question in the title....No. 

Well. Almost certainly no.

But hang on, I should fill in the back-story here.... the object causing all this fuss is pretty odd. Called 'Oumuamua' it's (we think) an asteroid... although it's probably the weirdest, most scientifically compelling, asteroid we've ever found. 

Oumuamua was spotted in mid October of 2017. At first it was a fairly unremarkable spot of light: Probably some small, dim comet that no-one had ever picked up on before, was what most astronomers thought. 

Then they plotted its course backwards, to see where it had originated from: Oumuamua came from outside our solar system - from interstellar space. And, if it came from outside our solar system then it was, originally, a piece of another star system. No-one has ever seen such an object before - a natural interstellar traveller. Computer simulations have tentatively suggested that about one such object should pass through our solar system every year, but to actually spot one was like actually filming a Sasquatch - a mythic beast, captured on film.  

  
Above: The course Oumuamua took through our solar system, passing right by Earth.

The weirdness then got weirder, turning from " minor but historic discovery" to "whoa.. what?". Firstly this asteroid had, as you can see in the video above, swung relatively close by Earth. That's interesting, but maybe not very surprising - if it hadn't been in our neighbourhood we might well have never spotted it. 
But its shape is what has got everyone's heads a-scratching: Asteroids and comets range from potato to ball shaped. But Oumuamua is a stick shape: Ten times as long (about 800 meters long) as it is wide. 

Sasquatch has sprouted a third leg, and wings.*  

Above: The odd shape of Oumuamua. 

The colour of the asteroid (which can be broken down to reveal clues to it's surface composition) is reddish. that implies the surface is covered in the same kind of organic molecules - the same kind implicated in the origin of early life on Earth - that we see on the surface of comets. But, unlike a comet, this object has no trace of vapour coming from it, or of any ice. That suggests it's a rocky or metallic object beneath the organics... but how that squares with its strange shape, extreme origin point, is anyone's guess. 

So we get to the crux of the question: This looks like no natural object we've ever seen. So could it be an artificial one? it's extremely unlikely. At present there is no news of any heat signature, radio or microwave emissions, or other behaviour suggesting technology. Its speed, whilst very high (26 km/ sec) is still very slow for an interstellar probe - although that is assuming any probe building aliens would have similar life spans to ours (and there's no reason to assume that really, they could live much longer and be much more patient). 

But none of that is confirmation of a natural origin either - and while that's the most likely scenario by a long way, it must still be a spectacularly unusual natural origin to have produced such a strange object. That means it could a be a window into some truly alien geological processes, happening far, far across the universe from us.... Not aliens, but very, very alien natural processes. For that reason the astronomical community is gathering all the information it can on this object, before it disappears beyond the range of our telescopes. And, just in case, Centauri dreams website reports that SETI (Search for Extra Terrestrial Intelligence) and Breakthrough Listen organisations are/have been keeping Oumuamua under observation. 

As they say, watch this space.... 

UPDATE: To make things even more interesting a mission to hunt down and examine Oumuamua (or any other interstellar asteroids) is being proposed - some details here.

The Universe in 101 words: Will we return to Saturn's moon Enceladus?

Above: Enceladus, an ocean world covered in ice.

Our solar system is awash* with ocean worlds. And thanks to the Cassini missionary we've gotten to know one, Enceladus a 500km wide moon of Saturn, really well.

So what's it ocean like?

Dark - the ocean's covered in 20km of ice - but maybe not totally black: There's volcanic activity on the ocean floor, possibly like the white smoker vents of Earth, so there'd be the dim carmine glow of volcanism. More importantly the salty, alkaline, water contains organic chemicals and hydrogen - food for possible micro-life.

Cassini's mission is over - but its now hard to imagine us not returning to Enceladus....

*Sorry.

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Above: The geysers of Enceladus, backlit: The ocean is literally leaking into space!