Starship Asterisk*

Zarmina s World

Explanation: A mere 20 light-years away in the constellation Libra, red dwarf star Gliese 581 has received much scrutiny by astronomers in recent years. Earthbound telescopes had detected the signatures of multiple planets orbiting the cool sun, two at least close to the system's habitable zone -- the region where an Earth-like planet can have liquid water on its surface. Now a team headed by Steven Vogt (UCO Lick), and Paul Butler (DTM Carnagie Inst.) has announced the detection of another planet, this one squarely in the system's habitable zone. Based on 11 years of data, their work offers a very compelling case for the first potentially habitable planet found around a very nearby star. Shown in this artist's illustration of the inner part of the exoplanetary system, the planet is designated Gliese 581g, but Vogt's more personal name is Zarmina's world, after his wife. The best fit to the data indicate the planet has a circular 37 day orbit, an orbital radius of only 0.15 AU, and a mass 3.1 times the Earth's. Modeling includes estimates of a planet radius of 1.5, and gravity at the planet's surface of 1.1 to 1.7 in Earth units. Finding a habitable planet so close by suggests there are many others in our Milky Way galaxy.

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In a way I think this is one of your very most important APOD's. It signifies discovery of a planet where life like ours might reasonably exist and that there could be a <b>lot</b> of them.

I wonder what is known, theorized or hypothesized about prospects for life around a red dwarf star.

Goldilocks question (the 1st Gliese 581g thread)
http://asterisk.apod.com/vie ... =8&t=21321

[quote=""potentially habitable plane found" link "]
"... The planet is tidally locked to the star, meaning that one side is always facing the star ..."
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I have learned about the 3 methods of detecting planets around stars, but how can you know it is tidally locked?

Brem2 wrote:I have learned about the 3 methods of detecting planets around stars, but how can you know it is tidally locked?

I think it is an assumption, but solidly based on the expected behavior of an Earth-mass rocky planet only 0.15 AU from its parent star.

The planet mass is estimated to be 3.1 times the mass of Earth. Could it be possible that the planet has a large moon, and that the estimated mass of 3.1 is the mass of the planet and the moon together?

Lynette Cook is a very talented artist. If the data for gliese 581g are indeed correct to any extent the planet will probably a world of perpetual cloud cover and violent storms. There will likely be two major cloud layers - and a region where the two layers clash producing continual lightning and rainstorm/icestorm.
Water must exist on a grand scale similar to the Earth - but a high concentration of noble gas must also exist. Speculation about the existence of life form in such a planet is irrelevent: the general interest is in the physical and dynamic qualities of such a world and whether these qualities are conducive to human habitation.

On October 12, 1492, while on Christopher Columbus's ship La Pinta, he sighted land of the Americas.[2]

After spotting America at approximately two o'clock in the morning, he is reported to have shouted "¡Tierra! ¡Tierra!" (land! land!)

20 light years-well now--I doubt any human will EVER get there-EVER
Space travel is something that really needs to be seriously looked at as farce.
Distances are to VAST
Radiation fields would probably kill us before we got far
Costs would be astronomical--that was a funny
and WHY?
We need to concentrate on MARS

Isn't it exciting! More and more planets are being found. Now there is one right in the middle of the habitable zone.

A nit: Since the star is a red dwarf, shouldn't the illuminated side of the planet be an orange color, instead of white?

Send a probe!

One of the statements of the discovery is the likelihood of liquid water. However, if it is tidally locked, wouldn't the water end up locked permanently on the dark side?

gpronger wrote:One of the statements of the discovery is the likelihood of liquid water. However, if it is tidally locked, wouldn't the water end up locked permanently on the dark side?

I suspect a planet such as the one described (in very little detail, it's true) would not be locking water away permanently, though a very long-time-scale cycle could be involved. Imagine a vast searingly hot desert facing the star, and a vast cold glacier on the away side of the planet. In between would be -- um, I think I'd call it interesting weather. Storms, floods, tornados, etc. A huge transfer of heat energy would be taking place constantly, throughout a belt all around the planet. Gradually the glaciers would push outwards, being replenished in the center. Gradually they'd melt at the edges, and gradually the melt water would flow out towards, but never satiate the thirst of the desert. It would be a very interesting planet. But it's too soon to say with any certainty what might be happening there -- not enough data.

Rob

If the planet is 3 times the mass of Earth, wouldn't we be crushed from the gravity?

nowskii wrote:If the planet is 3 times the mass of Earth, wouldn't we be crushed from the gravity?

The planet is also larger, and surface gravity drops with the square of the radius. Given the estimated mass and size of this planet, its surface gravity could be as little as 1.5g. A bit uncomfortable, but hardly crushing.

Three things …

First, I essentially copy and paste about 30% - 40% of the APODs, do a little editing, almost invariably add my “tutorials,” and send them on to a large number of friends, including quite a few young folks. One of my prejudices is that giving distances in light years is not very informative to novices who want to know about astronomy but don’t have the “requisite” technical backgrounds.

By way of example, the explanation above says “a mere 20 light-years away …” So we’re talking about a planet that possibly sustains life and it’s “just over there on the next block.” To make that distance a bit more meaningful to my readers, I edit it thusly …

“a mere 20 light years (i.e., 745,639 Astronaut Years) away …”

Most of my readers have difficulty interpreting how long it takes something traveling at the speed of light to traverse a certain distance, but an AY is the length of time it would take a crew of astronauts traveling at the maximum cruising speed of a space shuttle – and that’s the best we’ve done so far – to travel from Earth to the given object.

When APOD says “a mere 20 LY away,” an uninitiated reader might think, “Oh, WOW! … we’ll probably be exploring that place before long." But when you envision it as 745,639 AY, that casts it in a little different light … pun intended.

Oh yes – and I apologize to everyone for this – I convert everything to English units before sending the explanations on.

Second – and this may seem to be a bit off the subject – I have often thought about the prospect of using unusual force (like a nuclear weapon) to keep a “rogue” nation (like North Korea) from exacting unimaginable damage to another nation. I don’t know what it says about me, but I can imagine circumstances in which I could support that.

By the same token, however, I think we should consider annihilating with nuclear force any installation on Earth whose purpose is transporting life from this planet to another planet (even in “our” solar system). The quite awful damage that North Korea, for example, might inflict on another nation pales in significance to the damage homo sapiens could – and, I think, probably would -- inflict on another planet.

The extent to which we have taken the quite lovely planet, Earth, and screwed it up almost beyond recognition is reason enough not to turn us loose on other destinations in the Universe. “The moon is enough!” I say, “Enough!!!” When we learn to get along with each other and when we come to appreciate the importance, practices, and procedures of stewardship here on Earth; only then should we think about visiting other planets. What we don’t need is a bunch of macho jerks – and we have waaaaay more than our fair share of that species -- rushing off to Mars or Zarmina's World to either (1) exploit it for our purposes or (2) establish an outpost there because we have completely botched up our opportunities here and are looking for an escape. There are much worse outcomes in this Universe than the extinction of homo sapiens.

The prospect of there being planets about the Universe (besides Earth) that sustain “life” was thought to be a low probability event (in a relative frequency sense) just a few decades ago. But now we are apparently even finding some. Of course finding planets with “intelligent life” – whatever that might mean – is another matter altogether. And I think, given my first comment above, the (probably) non-intelligent life on Gliese 581 – assuming there is any – has little to fear from us for at least a few centuries … and, I hope, for the next 5 billion years.

Check out this wonderful Randall Monroe xkcd cartoon … http://xkcd.com/786/

R,W, Hoyer

Using our fastest rocket-propelled space craft, approximately how long would a one-way trip to Zarmina take ? Let's be realistic about extraterrestrial colonization !

durant1928 wrote:Using our fastest rocket-propelled space craft, approximately how long would a one-way trip to Zarmina take ? Let's be realistic about extraterrestrial colonization !

The fastest methods we can conceive of today -- not that we're capable of building any examples -- could move us at something close to 10% of the speed of light. Such a device, ignoring all other considerations, could get us to our nearest neighbour, Proxima Centauri (about 4.2 light-years away) in about 40 years. Zarmina is 20 ly away.

We're not ready for this sort of thing yet. We need to develop inter-planetary travel (that is, inside our own solar system) for the next hundred years or so before we'll have any reasonable idea of how to go about sending even a useful probe to our nearest stellar neighbours.

Rob

In doing analysis of the likelihood of the evolution of life as we know it on Zarmina's world, we should think about the spectrum of light put out by a Red Dwarf. Our sun puts out light with a peak in the center of our visual spectrum and shoulders of less brilliant light in higher and lower frequencies. I can't help but to think that the presence of UV light, while cancer causing to those of us who are alive, might have been necessary in the early stages of evolution.

A Red Dwarf should be putting off black body radiation with its peak in the Orange or Red area, the shoulders of which would likely leave very little out in the blue, purple and UV.

(But then, who knows, really, what makes life start?)

Well, if it is habitable, but not inhabited, then it could be our second home.

Chris Peterson wrote:

nowskii wrote:If the planet is 3 times the mass of Earth, wouldn't we be crushed from the gravity?

The planet is also larger, and surface gravity drops with the square of the radius. Given the estimated mass and size of this planet, its surface gravity could be as little as 1.5g. A bit uncomfortable, but hardly crushing.

Expected surface gravity ~ cube root of 3 ~ 1.44 g.

The animals/people would just be one third the mass (i.e., 30% shorter).

Craig Willford wrote:
In doing analysis of the likelihood of the evolution of life as we know it on Zarmina's world, we should think about the spectrum of light put out by a Red Dwarf. Our sun puts out light with a peak in the center of our visual spectrum and shoulders of less brilliant light in higher and lower frequencies. I can't help but to think that the presence of UV light, while cancer causing to those of us who are alive, might have been necessary in the early stages of evolution.

A Red Dwarf should be putting off black body radiation with its peak in the Orange or Red area, the shoulders of which would likely leave very little out in the blue, purple and UV.

(But then, who knows, really, what makes life start?)

Well, if it is habitable, but not inhabited, then it could be our second home.

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• The Chicken Roaster

Jerry knocks on Kramer's door. When the door is opened a huge
red light is seen, Kramer is there smoking away on a cigar]

Jerry: What's going on in there?

Kramer: Oh the red, its the chicken roaster sign, its right across my window.

Jerry: Can't you shut the shades?

Kramer: They are shut. Its killing me, I can't eat, I can't sleep,
all I can see is that giant red sun in the shape of a chicken.

Jerry: Well, did you go down to the Kenny Rogers and complain?

Kramer: Ah, they have me the heave ho.

[Kramer gets out a bowl, fills it with cereal
and then removes the tomato juice from the fridge.]

Jerry: What are you doing?

Kramer: Getting some cereal

Jerry: That's tomato juice.

[Kramer takes a big spoonful of cereal w/tomato juice!]

[Spits out cereal]

Kramer: That looked like milk to me!
Jerry my Rods and Cones are all screwed up!
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So what if Zarmina’s world is inhabited… and what if they are more advanced than us… doesn't the red stage of a star mean it is advanced in years? If so, it stands to reason that any intelligent life there would be advanced also. Therefore, if light year distances can be overcome then it also stands to reason that these advanced life forms could realistically transit interstellar distances. So why haven’t we been invaded? Maybe the answer lies in the possibility that an “advanced” civilization would have respect (or disdain) for indigenous life and therefore a reluctance to (or be absolutely against) interfering with a species that has such a wide range of cultural and social dispositions. Face it, we are a mess. Just look at Asterisk*… check out the range of posts… they illustrate just how different we humans are from each other. But on one common note… we quite often tend to digress into self indulgence and ostentation... not unlike this post… What did you do to entice an advanced alien today?

A Red Dwarf and a Red Giant are very different stars.

A Red Dwarf is a small star (smaller than our Sun) so that the nuclear furnace cooks more slowly because of decreased pressures at its core. As a consequence it is cooler and only red.

A Red Giant is a star in the final stages of life. It has used up much of its nuclear fuel and has switched to a different nuclear process, making even heavier elements than Helium. In the process, it bloats its surface far from its core and makes the star huge (and red).

Zarmina's world's star is reputed to be the former. It could be a young red dwarf or an old red dwarf. That info. hasn't been provided to us in this APOD entry.