Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Astronomers Discover Potentially Earthlike Planet Orbiting Binary Star

technologyreview.com

Post reply on HN
Print view View original

11–20 of 32 posts

Re: Astronomers Discover Potentially Earthlike Planet Orbiting Binary Star

#11

Post by iwwr »

retube wrote: post #4

Sensationalist headline. Actually just a candidate for supporting liquid water (and then only for some of it's fairly elliptic orbit). And it's pretty damn big, so not likely to be a rock, more like a gas giant (If it _doesn't _ have a large gaseous atmosphere it would I think be the biggest rock planet ever discovered.) So "habitable exo-planet" is stretching things............... a lot.

By its nature, a big rocky planet could hold on to a thicker atmosphere; it would also have greater internal heat, a thinner crust, so more geologic activity, greater volcanism.

Re: Astronomers Discover Potentially Earthlike Planet Orbiting Binary Star

#13

Post by jsvaughan »

JohnIdol wrote: post #3

"We're left, like the starving donkey equidistant between two bails of hay, unable to decide on what to celebrate" <-- the closest of these things is 20 light years :[

The scale of space is shocking. The fastest man made object, Helios 2 (http://goo.gl/xCow), at 250000kph, would take 17000 years to get to the next nearest star, Alpha Centauri.

This post by Charles Stross is worth a read: http://www.antipope.org/charlie/blog-static/2007/06/the_high...

To quote: "interstellar travel for human beings is near-as-dammit a non-starter"

Re: Astronomers Discover Potentially Earthlike Planet Orbiting Binary Star

#14

Post by Sharlin »

iwwr wrote: post #8

A red dwarf from 1000 au would only look like a moderately bright star, won't it? On the other hand, it would be close enough that if aliens inhabited, they could send a probe with present-day human level of technology. That is, the nearby star would serve as a stepping stone and an excuse to bridge the gap to interstellar space. Compare it to our Alpha Centauri, which lies just shy of 300K au, a relatively costly co…

A red dwarf from 1000 au would only look like a moderately bright star, won't it?

Indeed. The absolute magnitude of 55 Cancri B is 12.66, and the distance between the companions is 1065 AU [1]. Plugging these values to the magnitude equation yields a visual magnitude of about -3.78 [2], a little fainter than Venus at its minimum brightness [3].

[1] http://en.wikipedia.org/wiki/55_Cancri [2] http://orbitsimulator.com/formulas/vmag9.html [3] http://en.wikipedia.org/wiki/Apparent_magnitude#Table_of_not...

Re: Astronomers Discover Potentially Earthlike Planet Orbiting Binary Star

#15

Post by danking00 »

cryptoz wrote: post #10
radarsat1 wrote: post #9

In the habitable zone 74% of its orbit? Although it sounds great, I'm left skeptical: to support life, wouldn't that need to be 100%?

It doesn't need to be 100% if the atmosphere of the planet could keep enough heat for the remaining 26% of the time, which is entirely likely. This find is awesome, but it's not what the headline describes. The planet is no "ExoEarth". It's a fantasticly cool exoplanet that could very probably support life that vaguely resembles life on Earth (not humans, though).

It looks like the planet actually slides closer in to the star, thus the issue would be keeping the environment cool enough.

Re: Astronomers Discover Potentially Earthlike Planet Orbiting Binary Star

#16

Post by cosgroveb »

iwwr wrote: post #8

A red dwarf from 1000 au would only look like a moderately bright star, won't it? On the other hand, it would be close enough that if aliens inhabited, they could send a probe with present-day human level of technology. That is, the nearby star would serve as a stepping stone and an excuse to bridge the gap to interstellar space. Compare it to our Alpha Centauri, which lies just shy of 300K au, a relatively costly co…

I probably did the calculations[1] wrong but the value I'm getting for the apparent magnitude of 55 Cancri B at 1000 AU with an absolute magnitude of 12.66[2] is about -3.9121 which, if located in our Solar system, would be bright enough to see in daylight, despite being almost 35 times as distant as Pluto is to the Sun.

[1] http://ceres.hsc.edu/homepages/classes/astronomy/spring99/Ma... [2] http://en.wikipedia.org/wiki/55_Cancri

Re: Astronomers Discover Potentially Earthlike Planet Orbiting Binary Star

#17

Post by Roboprog »

danking00 wrote: post #15
cryptoz wrote: post #10

Earlier quoted context omitted.

It doesn't need to be 100% if the atmosphere of the planet could keep enough heat for the remaining 26% of the time, which is entirely likely. This find is awesome, but it's not what the headline describes. The planet is no "ExoEarth". It's a fantasticly cool exoplanet that could very probably support life that vaguely resembles life on Earth (not humans, though).

It looks like the planet actually slides closer in to the star, thus the issue would be keeping the environment cool enough.

Closer to a smaller, cooler star.

Re: Astronomers Discover Potentially Earthlike Planet Orbiting Binary Star

#18

Post by iwwr »

cosgroveb wrote: post #16
iwwr wrote: post #8

A red dwarf from 1000 au would only look like a moderately bright star, won't it? On the other hand, it would be close enough that if aliens inhabited, they could send a probe with present-day human level of technology. That is, the nearby star would serve as a stepping stone and an excuse to bridge the gap to interstellar space. Compare it to our Alpha Centauri, which lies just shy of 300K au, a relatively costly co…

I probably did the calculations[1] wrong but the value I'm getting for the apparent magnitude of 55 Cancri B at 1000 AU with an absolute magnitude of 12.66[2] is about -3.9121 which, if located in our Solar system, would be bright enough to see in daylight, despite being almost 35 times as distant as Pluto is to the Sun. [1] http://ceres.hsc.edu/homepages/classes/astronomy/spring99/Ma... [2] http://en.wikipedia.org/w…

Still, it won't look like 'two suns in the sky', but more like Venus.

Re: Astronomers Discover Potentially Earthlike Planet Orbiting Binary Star

#19

Post by cosgroveb »

iwwr wrote: post #18
cosgroveb wrote: post #16

Earlier quoted context omitted.

I probably did the calculations[1] wrong but the value I'm getting for the apparent magnitude of 55 Cancri B at 1000 AU with an absolute magnitude of 12.66[2] is about -3.9121 which, if located in our Solar system, would be bright enough to see in daylight, despite being almost 35 times as distant as Pluto is to the Sun. [1] http://ceres.hsc.edu/homepages/classes/astronomy/spring99/Ma... [2] http://en.wikipedia.org/w…

Still, it won't look like 'two suns in the sky', but more like Venus.

Definitely. It would look like a pretty damn bright star, but not like a second Sun.

Re: Astronomers Discover Potentially Earthlike Planet Orbiting Binary Star

#20

Post by ck2 »

Maybe in 50 years we can get probes up to 10% light speed.

200-250 years to reach the planet and then another 20 years for the signal to get back (if we can somehow make a signal strong enough).

So 300 years from now our great-great-grandchildren might know (that's 70 years longer than US history).

But we'd actually have to spend some of that war and terrorism industry money on NASA and private investment to accomplish that. Not sure the politicians would ever bother.

Post reply on HN