The Twilight's Last Gloaming

They've been breathless. Media organs worldwide have put out article after article about the discovery of an "Earth-like" planet orbiting Gliese 581, a red dwarf star twenty light-years from here: just down the street in astronomical terms. This isn't the first time that system had been the center of attention - last year the discovery of Gliese 581 e, orbiting on the outer edge of the star's habitable zone, marked the smallest planet yet discovered. It didn't take long for Gliese 581 g to break this record; the planet - quickly dubbed "Gloaming" by io9, which is admittedly a far more interesting name than "Gliese 581 g" - orbits well within the star's small "habitable zone," that being the area where the existence of liquid water on the surface is possible.

A chart of the Gliese 581 system superimposed on the inner Sol system. This image is a work of a National Science Foundation employee, taken or made during the course of the person's official duties. As a work of the U.S. federal government, the image is in the public domain.

The only problem is that the scientific vocabulary doesn't exactly intersect with the standard vernacular; indeed, there are plenty of occasions where a scientific term can easily be interpreted as something completely different by a layman. When scientists say "Earth-like," they mean that it's a rocky planet roughly similar in size to Earth. As far as the media is concerned, calling it "Earth-like" means we're just one breakthrough in theoretical physics away from being to sell vacation timeshares there.

Because really, it's "Earth-like" in many of the same ways that Mars is Earth-like. It orbits so close to its sun that it's tidelocked in the same way that Luna always presents the same face to Earth - one hemisphere of Gloaming is in constant light and the other in constant darkness, with only a thin "twilight band" around the terminator presenting the possibility of a more moderate climate. What's more, its surface gravity is likely even stronger than Earth's, presently estimated at between 1.1 and 1.7 g... and you thought launching stuff to orbit from Earth was expensive! That is, if anyone would want to live there in the first place: from what I've read, the extrapolated environmental conditions in the twilight band are disturbingly reminiscent of Yellowknife in December.

I don't know about you, but I think I've been down this road before - anyone else remember 70 Virginis b? It occupied the news for a brief time back in 1996, when it was believed it orbited within its own star's habitable zone, until further measurements refined our understanding of a far more elliptical, and far less salubrious, orbit. Admittedly the evidence for Gloaming's potential habitability is greater - but that's still all it is. While I think it's a bit early to throw Earth 2 marathons in honor of the discovery, I do find it comforting that so many people do seem so excited about this prospect.

What Gloaming's discovery really makes clear to me is that there's a massive eagerness for us to be told, authoritatively, that We Are Not Alone - or, failing that, that we've discovered where They might live, or have lived, or be yet to live, considering that technological civilizations would likely be separated just as vastly by time as they would by space.

Nevertheless, it's still an inspiring discovery. We've spent decades, centuries even, looking up at the night and guessing at what's there, hidden beyond our sight. Gloaming won't be the last we find, and in the meantime we need to encourage this interest, this thirst to know and understand what's out there, beyond. In a world of unstable economic recovery, an uncertain present, and unchecked greed, it's helpful to be able to look through our telescopes and see the future.

Looking Ahead In An In-Between Universe

Seventy years ago - and damn, but is it going to take me a while to get used to 1940 being "seventy years ago" now - neither writers nor readers batted an eye at the prospect of canals on Mars, jungles on Venus, or intelligent species scattered across the solar system. It wasn't until the latter half of the 20th century, when more sophisticated Earth-based detection systems were developed and the first interplanetary probes were launched, that Barsoom was transformed from possibility to fantasy.

Being proven wrong is an eventuality that every sf writer will face. It's an intrinsic fact of the genre; we're none of us clairvoyants, and though some may forecast more accurately than others, what we put down in our words can't ever match the future that will eventually unfold. It's too complicated for that. What sf writers can do, however, is try to minimize this as much as possible.

Right now, the stories I've got in the working or planning stages are relatively near future pieces, set in the Earth-Luna system in the late 2070s. For a while I've had plans to go further afield once I develop the setting, to do 22nd-century stories where distant interplanetary and even interstellar journeys become possible. The stars beyond Sol have been ciphers for all of human history - for almost all of the time that science fiction has been written, Earth's intrepid explorers might find anything under other suns.

This decade might see this change a bit. NASA's Kepler telescope, launched last March on a multi-year mission to discover strange new worlds, has been hard at work, and on Monday details were released of the five new exoplanets detected by its efforts. All five of the newfound planets are hot worlds, orbiting extremely close to their parent stars, and only one is smaller than Jupiter. Going back to the discovery of Bellerophon in 1995, many of the exoplanets so far detected have been such "Hot Jupiters." Kepler is poised to change that, with its sensitive instruments said to be capable of detecting Earth-mass planets orbiting other stars. Not only that - in the near future, telescopes may well be able to detect individual moons orbiting these gas giants. Presumably, only the exotic properties of the mass relays will prevent Kepler from detecting them as well.

While this is great news to me, as a scientifictionist it poses a problem for the immediate future. Back in 1940, spaceflight itself was widely considered a fool's dream - whether or not Mars had canals and Venus jungles, if the writers of the time were concerned about accuracy, for all they knew it might have been a hundred years until they were proven wrong or right either way. I feel like I'm in a similar place now as to when Larry Niven wrote and sold The Coldest Place in 1964, written when the leading consensus was that Mercury was tidally locked, a consensus that was only broken by radar mapping - and after The Coldest Place had been bought, but before it was published.

I ran into a similar problem while writing You Source of Tears, which will be appearing in an upcoming issue of On Spec magazine. Originally it was set around Halley's Comet, though the only artifact of this is the title itself. I changed the setting to the fictional Comet Veale for two reasons - one, because a three hundred-year orbital period was more convenient for me than Halley's seventy-six, and two, because there was the possibility that some future expedition to Halley's Comet would prove me wrong. As an sf writer, I make enough assumptions about the future already - there's no need for me to dump falsifiable predictions into the mix.

Kepler, if successful, will revolutionize our understanding of the interstellar neighborhood. In ten years, maybe we'll know that a planet of Tau Ceti or a moon of a gas giant at 55 Cancri has an oxygen-nitrogen atmosphere and liquid water. We wouldn't be speculating blind anymore, and while we may end up just building new Barsooms, there's a certain magic in that. I'm willing to hold my pen until they make the first maps of those strange new worlds.

Stars of Other Worlds: Iota Horologii

Every once in a while, Acts of Minor Treason takes a jaunt through subspace and hyperspace and across cosmic strings and collapsars to some strange new world, to set up a telescope and look up at the stars from a new angle.

When a friend asked where I found the tribble, I answered, "Iota Horologii IV. Where did you think I found it?" That story held up until the stark, terrifying realization that tribbles are from Iota Geminorum IV. My hyperspace nav had a few fresh dents the next day, I can tell you. Still, I can assure you that while there are no tribbles to be found in the Iota Horologii system, it is theorized to be the site of Installation 04, the Forerunner ringworld destroyed by Master Chief in the original Halo.

You've probably never heard of Iota Horologii. Hell, you've probably never heard of the constellation Horologium, unless you're one of my few Southern Hemispheran readers. To put it simply, Horologium is supposed to be a clock but looks nothing like one, and Iota Horologii is a G0V yellow dwarf star broadly similar to Sol, 56.2 light-years away. Its Wikipedia article calls it a "solar twin" like HD 98618, but since the evidence suggests Iota Horologii is less than seven hundred million years old, that's really straining the term. Nevertheless, it's interesting enough that it was #69 on the Terrestrial Planet Finder's list of stars, until that potential observatory was eviscerated on the table.

What it does mean, though, is that unless the Precursors tore through and terraformed the place, it's highly unlikely there's any life more complex than microbes in the Iota Horologii system. However, one planetary companion has been detected, and like 55 Cancri f it orbits within the star's habitable zone. It could be that for extrasolar colonies, moons are where it's at after all. In the end, if anyone's going to be looking at its constellations any time soon, they'll probably be human or of human descent.

The images presented here include all stars with an apparent magnitude of 6.4 or greater. 6.5 is the limit for visibility to the naked eye under perfect conditions. Also, unlike previous Stars of Other Worlds segments, I've consolidated the unlabelled and labelled constellations into individual images here. If you've got any comments on which format you prefer, giving them would be totally rad.

Triangulum Magnum

If the Precursors had terraformed a world in Iota Horologii, and they'd scooped up some Atlanteans or Tartessians or other "ancient magical societies" to settle there, they'd probably see significance in this pattern of stars. Perhaps this is the True Mystic Triangle, and when it is high in the sky a wizard can tap Power unimaginable.

Or maybe it's just three bright stars that stand out in a recognizeable pattern, taking up about the same chunk of sky as Orion.

There's also a bit of honest astronomical interest to this constellation. Chi Eridani at the top is, with a separation of 7.29 light-years, Iota Horologii's closest known stellar neighbor. What's more, with an apparent magnitude of -0.78, it's brighter than all Earth's night sky stars but Sirius, and is the second-brightest star in Iota Horologii's sky; only Canopus outshines it.

Nevertheless, I can understand that while a triangle's a natural shape, it's also boring. There are plenty of other things Triangulum Magnum COULD be, after all - a d4! A pyramid! Alternatively, add Beta Capricorni into the design and you've got yourself a poorly-made Shofixti Scout.

The Penitent Knight

I keep coming back to the stars of Orion out of a sort of "repertory theatre" view of the sky: some stars will always have the important roles. From Iota Horologii their pattern's hardly as obvious and striking as HD 98618's Heavenly Scimitar, but I wasn't about to let that stop me. I've done far too many constellations that actually resemble what they're supposed to be; as far as I'm concerned, the Penitent Knight is one of those "just take my word for it" constellations, just like back home!

See, this is how it goes. Delta Orionis forms his head, and Zeta, Epsilon, and Eta Orionis his neck and shoulders. Rigel, just slightly brighter than it appears from Earth, is the foot on which he's kneeling, and Mu Leporis, Kappa Orionis, and Beta Leporis make his other leg. Theta¹ Orionis C and Iota Orionis form the scabbard for his sword. Some may say that it could be longer, but they are sadly mistaken and wrong. What Celestia doesn't reflect here is the presence of the Orion Nebula; in Iota Horologii's real sky, it would be centered around the scabbard stars.

You may notice that Betelgeuse, the blood-red second-brightest star of Orion, is not in this picture. It's actually out of frame, "above" Delta Orionis, where it is busy chilling with Bellatrix. The same stars can't all hang out together all the time, you know.

The Great Fish of the Galaxy

This ain't your father's Pisces.

Originally this constellation was to be known as the Trumpet of Stars, because that's what I first saw when I saw it, and I would just have explained it away as having been named by someone who didn't really know what a trumpet was other than "thing with big horn," and who was probably thinking of a tuba anyway.

It wasn't until I'd made the lines that I realized what else they made. It vaguely resembles an ichthys, and reminds me of the fish cutouts I'd make on construction paper, glue googly eyes to, and present to my mom as if I'd personally fished them out of Kempenfelt Bay. That it's "swimming" in the visible galaxy only made it more appropriate.

Like Sagittarius, most of the Great Fish of the Galaxy's stars can be found very near to the galactic core as viewed from Iota Horologii. It's not the most striking in the sky - its brightest member, Epsilon Sagittarii, has an apparent magnitude of 1.83, with the rest generally second- or third-magnitude stars - but, unlike the Penitent Knight, it actually looks like what it's supposed to be. Presumably, in myth and legend, it is the trickster rival of the Great Bird of the Galaxy.

Though, now that I look at it again, it could just as easily be a caricatured Apollo service module.

Incidentally, there's just one more thing I wanted to show you - not a constellation. But it's something that's always at the back of my mind. Remember, fifty-six light-years is a long,


long,



way.


Distant Stars of Other Worlds

• 55 Cancri
  
• HD 98618

Thank you for reading this far! Be advised that you can now reach this weblog through a new URL, www.actsofminortreason.com. It is all mine, ALL MINE!

Stars of Other Worlds: 55 Cancri

Every once in a while, Acts of Minor Treason takes a jaunt through subspace and hyperspace and across cosmic strings and collapsars to some strange new world, to set up a telescope and look up at the stars from a new angle.

Though I was a star nerd during my youth - I learned the Greek alphabet from Terence Dickinson's Nightwatch, and pored over its starcharts religiously even though I never mustered the gumption to actually take the telescope out for a spin - it wasn't until the 21st century that I first heard of 55 Cancri. Also known as Rho¹ Cancri, 55 Cancri is a binary star in the constellation Cancer, approximately forty-one light-years away. The larger of the two stars is a G8V yellow dwarf, a bit dimmer than our own sun, and it's accompanied by a much dimmer red dwarf. From Earth, 55 Cancri A has an apparent magnitude of 5.95, just barely visible to the naked eye under ideal conditions.

The stars themselves aren't too remarkable. Binaries are, after all, one of the most common stellar arrangements in the galaxy. The 55 Cancri planetary system, on the other hand, is something else entirely. It's the largest known system beyond the solar system, with at least five planets detected in orbit of 55 Cancri A, all thought to be gas giants based on their mass. One of them, 55 Cancri f, orbits its sun in 260 days and spends its orbit entirely within the habitable zone - close enough to the sun that a hypothetical moon of the planet could sustain liquid water, which might enable an ecosphere similar to Earth's.

So, hypothetically, if there are thinking beings on a moon of 55 Cancri f - whether they're humans or otherwise - what would they see?

There'll always be the stars. Earth and 55 Cancri are close enough to share bright stars in common - Canopus is effectively just as bright when viewed from either system, and Rigel and Betelgeuse in Orion are a bit dimmer here than there. Discounting 55 Cancri B, when observing from a moon of 55 Cancri f Pollux would be the brightest star in the sky, a bit dimmer than Sirius appears on Earth.

Still, even though Sol and 55 Cancri occupy the same galactic neighborhood, perspective changes fast with only a handful of parsecs. While snooping around in its sky I found two constellations that struck my interest, constellations I've named the Broken Plough and Atalanta.

The Broken Plough

Aside from Orion, the Big Dipper is probably the single most recognizable star pattern in Earth's skies. It's known by many names by many cultures, and in the British Isles it's also called the Plough. As many of its stars move together in a cluster called the Ursa Major Moving Group, it's no surprise that from 55 Cancri they're still together in the sky. Even the pattern we're familiar with on Earth is mostly intact - if a bit distorted.


Viewed from Earth, the two brightest Big Dipper stars are Dubhe and Alioth, which share an apparent magnitude of 1.8. Although Dubhe doesn't figure into the Broken Plough as I've laid it out, Alioth is its keystone and even brighter than we see it, with an apparent magnitude of 1.22 from 55 Cancri. Alkaid, at the western end, is still brighter than any of the Big Dipper stars from Earth, and Thuban - the brightest star in Draco, and the northern polestar in ancient Egypt's heyday - at the eastern edge is only slightly dimmer than Megrez seems to us, and again is somewhat brighter than it appears from Earth.

Atalanta

In Greek mythology, Orion was a masterful hunter who was killed either by Artemis (who, presumably, did not like competition of Orion's caliber) or a giant scorpion and subsequently elevated to the heavens in the form of the constellation we know today. He's one of the many larger-than-life heroes that populate the myths - taken together, they're a real sausagefest, if you ask me.

Orion the constellation has such mythological significance because it's so damned obvious. Owing to its position in the sky it's visible in every part of the world, and it's anchored by some of the brightest stars in the sky. Bright patterns like that definitely attract attention.

Should there ever be humans looking up from a moon of 55 Cancri f, they might not take long to notice a particular arrangement of stars that reminds them of what they left behind.


In Greek mythology, Atalanta was also a hunter, and one of the few non-goddess females in that canon. The correspondence isn't exact, but haunting nevertheless. Antares, at her right foot, is Atalanta's brightest star, with Graffias (Beta Scorpii) her head while Zubenelgenubi and Sigma Scorpii form her belt. Here, Atalanta comprises stars from no less than three Earth constellations - while the majority are in Scorpius from Earth's perspective, Zubenelgenubi is the brightest star in Libra, and Atalanta's left foot is formed by Gamma Virginis, in Virgo.

This correspondence is particularly interesting because none of the familiar stars of Orion are involved in it. Still, the human brain is the most sophisticated finder of patterns in the static that we have, and it's no suprise that on distant worlds we might look up to see something that, while not the same, remains vaguely familiar - enough to put one at ease, remembering home.

What of home, by the by? Forty-one light-years is hardly enough to make a star like ours invisible. Sol's above the limits of vision from 55 Cancri, but not by much - it would have an apparent magnitude of 5.32, best viewed with binoculars.

As previously, all glory goes to Celestia for making these views possible without a hell of a lot of painful mathematics on my end.

Further Stars of Other Worlds

• HD 98618