APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Comments and questions about the APOD on the main view screen.
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APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by APOD Robot » Thu Aug 25, 2016 4:11 am

Image Closest Star has Potentially Habitable Planet

Explanation: The star closest to the Sun has a planet similar to the Earth. As announced yesterday, recent observations confirmed that this planet not only exists but inhabits a zone where its surface temperature could allow liquid water, a key ingredient for life on Earth. It is not yet known if this planet, Proxima b, has any life. Even if not, its potential ability to sustain liquid water might make it a good first hop for humanity's future trips out into the Milky Way Galaxy. Although the planet's parent star, Proxima Centauri, is cooler and redder than our Sun, one of the other two stars in the Alpha Centauri star system is very similar to our Sun. The featured image shows the sky location of Proxima Centauri in southern skies behind the telescope that made many of the discovery observations: ESO's 3.6-meter telescope in La Silla, Chile. The discovered planet orbits close in -- so close one year there takes only 11 days on Earth. The planet was discovered by the ESO's Pale Red Dot collaboration. Although seemingly unlikely, if Proxima b does have intelligent life, at 4.25 light years distance it is close enough to Earth for two-way communication.

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by bystander » Thu Aug 25, 2016 4:15 am

Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by Ann » Thu Aug 25, 2016 4:28 am

Proxima Centauri is a weird star, compared with our Sun. But it might be more "average" as stars go in the Milky Way than our own Sol.

Proxima is about one part in 18,000 as bright as our Sun in optical light. If we factor in infrared light, it is about one part in 600 as bright as our Sun.

Proxima Centauri is a flare star. That means that it can suddenly release a sudden burst of energy that briefly makes it perhaps twice as bright as it normally is. That wouldn't be healthy for any surface-dwelling beings on Proxima Centauri b, but perhaps life could still exist and thrive underground.

We should definitely put a lot of effort into finding out more about Proxima Centari b.

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by old dude » Thu Aug 25, 2016 4:57 am

It is a nice planet, just avoid the New Earth island with its seductive inhabitants.

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by RocketRon » Thu Aug 25, 2016 6:20 am

If it orbits a mere 7 million kilometres from Proxima Centauri, as reported, is it really going to be cool enough for 'liquid water' ?

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by Ann » Thu Aug 25, 2016 7:47 am

RocketRon wrote:If it orbits a mere 7 million kilometres from Proxima Centauri, as reported, is it really going to be cool enough for 'liquid water' ?
Proxima Centauri itself is very much cooler than the Sun. So yes, 7 million kilometers from Proxima could be just right for liquid water.

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by Guest » Thu Aug 25, 2016 8:01 am

OK, so it is probably close enough to get a probe out to it. It would take a long time in human terms, but it may be possible. What I am wondering is, would we (or our grand kids) be able to communicate with the probe at that distance? Would a probe have enough power for that? Would it be able to overcome the background noise of the galaxy/universe?

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by RocketRon » Thu Aug 25, 2016 8:37 am

If its 'only' 4.25 light years distant, and a probe like say New Horizons (Pluto) were sent out to it,
at a reported speed of ~50,000 mph (?) then a quick back of the stamp calculation says it would take
~ 4000+ years to get there ! (about a 1000 earth years per light year).
Some of the press reports sound like this is feasible and planned already... !
It would also need to carry enough fuel to be able to put the brakes on when it gets there, to avoid overshooting.

Since comms travel at the speed of light, any messages would reach it in 4.25 years once there,
and 4.25 years for the return message.
We had better leave our descendants a note on the fridge to remind them to listen out for it.

Stress this was a back of a stamp calculation, if there are any fundamental errors or large orders of
magnitude out then please point them out.
This also assumes that that 4.25 light years distance is indeed correctly calculated.

P.S. How long before someone suggests we send a manned mission ?!

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by neufer » Thu Aug 25, 2016 9:33 am

Guest wrote:
OK, so it is probably close enough to get a probe out to it. It would take a long time in human terms, but it may be possible. What I am wondering is, would we (or our grand kids) be able to communicate with the probe at that distance? Would a probe have enough power for that? Would it be able to overcome the background noise of the galaxy/universe?
Good question.

1) Voyager 1 is communicating from 135 AU away in the X band at 8.4 GHz. If the D band were used instead a 168 GHz beam would be 20 times narrower and extend out to perhaps to 2700 AU. (A large drop in the data rate could get one much further.)

2) NASA is currently experimenting with laser communication systems.

3) If laser propulsion from the Earth is used on a very small spacecraft then simply adjusting the spacecraft's reflection could be used.
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by hamilton1 » Thu Aug 25, 2016 9:36 am

RocketRon wrote:If its 'only' 4.25 light years distant, and a probe like say New Horizons (Pluto) were sent out to it,
at a reported speed of ~50,000 mph (?) then a quick back of the stamp calculation says it would take
~ 4000+ years to get there
Sorry RocketRon, 50000 mph is half a billion miles per year. Proxima is 25 trillion miles away so that will take 50,000 years.

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by neufer » Thu Aug 25, 2016 9:49 am

hamilton1 wrote:
RocketRon wrote:
If its 'only' 4.25 light years distant, and a probe like say New Horizons (Pluto) were sent out to it,
at a reported speed of ~50,000 mph (?) then a quick back of the stamp calculation says it would take
~ 4000+ years to get there
Sorry RocketRon, 50000 mph is half a billion miles per year. Proxima is 25 trillion miles away so that will take 50,000 years.
rstevenson wrote:
One light-year is about 63,240 AUs, and Proxima Centauri is about 4.2 ly from here, or about 265,600 AUs by this calculation. Using 265,600 AUs, I get about 74,700 years to get there if our interstellar probe is moving about as fast as New Horizons.
After multiple gravity assists the 5,600 kg Cassini spacecraft finally left the Earth/Moon system just ~3 km/s shy of Solar System escape velocity. Presumably a Saturn V could place a 47,000 kg spacecraft into a similar (near solar system escape velocity) trajectory. Such a 47,000 kg spacecraft could (given an effective Xenon ion exhaust velocity (Ve) of 29 km/s) launch a ~800 kg interstellar probe that escapes the solar system at a velocity of 120 to 150 km/s = a relative velocity vis-a-vis α Centauri of 140 to 170 km/s. Such a probe could reach α Centauri (or Barnard's star) in from 7700 to 9400 years.
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by Chris Peterson » Thu Aug 25, 2016 2:41 pm

Ann wrote:Proxima is about one part in 18,000 as bright as our Sun in optical light. If we factor in infrared light, it is about one part in 600 as bright as our Sun.
Of course, from a habitability standpoint, all that matters is the energy reaching the surface of a planet.
Proxima Centauri is a flare star. That means that it can suddenly release a sudden burst of energy that briefly makes it perhaps twice as bright as it normally is. That wouldn't be healthy for any surface-dwelling beings on Proxima Centauri b, but perhaps life could still exist and thrive underground.
That's not obvious. If the Sun occasionally doubled its intensity for a few seconds, I don't imagine it would have any significant impact on surface life. Looking at the entire biosphere, there's more than a twofold difference in solar intensity at any time.
Last edited by Chris Peterson on Thu Aug 25, 2016 3:25 pm, edited 1 time in total.
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by neufer » Thu Aug 25, 2016 3:02 pm

Chris Peterson wrote:
Ann wrote:
Proxima is about one part in 18,000 as bright as our Sun in optical light. If we factor in infrared light, it is about one part in 600 as bright as our Sun.
Of course, from a habitability standpoint, all that matters is the energy reaching the surface of a planet.
From a liquid water standpoint, what matters is the energy absorbed by the surface of a planet (both from sunlight and from the atmosphere).

From a habitability standpoint, the fact that most of the energy is in the form of high frequency/low entropy radiation is also somewhat important. (You can't make an omelet without cracking some eggs.)
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by Chris Peterson » Thu Aug 25, 2016 3:24 pm

neufer wrote:
Chris Peterson wrote:
Ann wrote:
Proxima is about one part in 18,000 as bright as our Sun in optical light. If we factor in infrared light, it is about one part in 600 as bright as our Sun.
Of course, from a habitability standpoint, all that matters is the energy reaching the surface of a planet.
From a liquid water standpoint, what matters is the energy absorbed by the surface of a planet (both from sunlight and from the atmosphere).
Not necessarily. There are other sources of energy that can keep water liquid. A body with liquid oceans covered with ice needs neither atmosphere nor significant solar heating.
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by neufer » Thu Aug 25, 2016 3:41 pm

Chris Peterson wrote:
There are other sources of energy that can keep water liquid. A body with liquid oceans covered with ice needs neither atmosphere nor significant solar heating.
Of course... and such sources of energy can also provide the a source of low entropy for habitability.
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by Boomer12k » Thu Aug 25, 2016 5:54 pm

Assuming the "intelligent" life has had a similar technology level and evolution,.... and the desire to communicate with others.... if they ARE intelligent..... THEY WOULD BE FOOLS TO CONTACT US!!!!!!!!

When will we EVER learn???

Great project, and hopeful.... they laughed at me in the 70's, in Science Lab, when I did a report on the possibility of planets in the galaxy... now they say there is ONE NEXT DOOR, AND IT MIGHT BE ABLE TO HARBOR LIFE!!!!! JOKES ON THEM.....GNGGNNNNNNNNNHHHH!!!! :p:

Yeah, I know.... Let it go, Boomer....
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by Boomer12k » Thu Aug 25, 2016 5:57 pm

Hmmmm.... let's see..... 11 days to a year..... 365/11 = 33.181818181818.... at 63 Earth years old... that would make me....2090.34 years old there..... EWWWWWW.... OLD GUY, MUCH?????? I don't think I like the math of that science....

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by Chris Peterson » Thu Aug 25, 2016 6:03 pm

Boomer12k wrote:Assuming the "intelligent" life has had a similar technology level and evolution,.... and the desire to communicate with others.... if they ARE intelligent..... THEY WOULD BE FOOLS TO CONTACT US!!!!!!!!
Not sure about that. They might find us very tasty.
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by Boomer12k » Thu Aug 25, 2016 6:06 pm

So... Spectrums Wobble, but they don't fall down????

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by Chris Peterson » Thu Aug 25, 2016 6:13 pm

Boomer12k wrote:So... Spectrums Wobble, but they don't fall down????
They do. That's what cosmological redshift is... spectrums falling down.
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by Boomer12k » Thu Aug 25, 2016 6:23 pm

Chris Peterson wrote:
Boomer12k wrote:Assuming the "intelligent" life has had a similar technology level and evolution,.... and the desire to communicate with others.... if they ARE intelligent..... THEY WOULD BE FOOLS TO CONTACT US!!!!!!!!
Not sure about that. They might find us very tasty.

And THAT would make US the fools.... "It's a COOKBOOK"....

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by luxorion » Thu Aug 25, 2016 6:39 pm

To illustrate these comments, here are two renderings of Proxima b :

Image
Cheers,
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by neufer » Thu Aug 25, 2016 7:09 pm

Click to play embedded YouTube video.
Boomer12k wrote:
Chris Peterson wrote:
Boomer12k wrote:
Assuming the "intelligent" life has had a similar technology level and evolution,.... and the desire to communicate with others.... if they ARE intelligent..... THEY WOULD BE FOOLS TO CONTACT US!!!!!!!!
Not sure about that.
They might find us very tasty.
And THAT would make US the fools....
"It's a COOKBOOK"....
  • Well, if you wanted to make Serak the Preparer cry, mission accomplished.
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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by heehaw » Thu Aug 25, 2016 8:49 pm

Don't bother to launch a probe to this planet. A complete and utter waste of effort. Why? Because it would take SO long to get there, we humans would have send MUCH MUCH better and FASTER probes later, like 10 years from now, or 110 years from now. You'd be launching museum exhibits.

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Re: APOD: Closest Star has Potentially Planet... (2016 Aug 25)

Post by geckzilla » Thu Aug 25, 2016 8:58 pm

heehaw wrote:Don't bother to launch a probe to this planet. A complete and utter waste of effort. Why? Because it would take SO long to get there, we humans would have send MUCH MUCH better and FASTER probes later, like 10 years from now, or 110 years from now. You'd be launching museum exhibits.
Keeping and maintaining the ability to communicate with a probe on such a long term mission remains a problem whether it's launched a decade from now or a century.
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