11–20 of 305 posts
Is there any benefit to the planets being earth-sized? I would think the important part is that they're in the habitable zone.
This title is a bit imprecise. They detected four planets with lower bound on their masses to be down to 1.7 Earth masses. Because these planets don't transit, there are no direct measurements from their radius. They can use mass-radius relations to infer the radius of these planets, but the key finding is their masses (actually lower bounds on their masses).
Key line to mitigate disappointment: "The outer two planets around tau Ceti are likely to be candidate habitable worlds, although a massive debris disc around the star probably reduces their habitability due to intensive bombardment by asteroids and comets."
Is there any benefit to the planets being earth-sized? I would think the important part is that they're in the habitable zone.
This title is a bit imprecise. They detected four planets with lower bound on their masses to be down to 1.7 Earth masses. Because these planets don't transit, there are no direct measurements from their radius. They can use mass-radius relations to infer the radius of these planets, but the key finding is their masses (actually lower bounds on their masses).
Can you say they _don't_ transit? They say the planets were detected by analyzing star wobbles, which doesn't necessarily mean that the planets don't transit, just that it's not how they were detected.
"In astronomy, a transit or astronomical transit is the phenomenon of at least one celestial body appearing to move across the face of another celestial body, hiding a small part of it, as seen by an observer at some particular vantage point."[0]
Hearing distances like 12 light years makes you think if it is ever possible to travel there. However, when you start to think about it, nihilist thoughts start to kick in.
With the EMdrive it'll take around 150 years (give or take a century), so it's within the realm of possibility if we can engineer a ship with shielding that can last that long. The mission becomes an order of a magnitude more difficult if you want to put a viable human population on it... watch Pandorum for one scenario.... perhaps it's best to send a seed ship (as written about in the excellent SF story by Pamela Sa…
Is there any benefit to the planets being earth-sized? I would think the important part is that they're in the habitable zone.
The fastest spacecraft ever built would take 4000 years to travel one light year.
Is there any benefit to the planets being earth-sized? I would think the important part is that they're in the habitable zone.
Gravity. A rocky planet, roughly Earth-sized, will have about the same gravity as we have on Earth. Both larger and smaller planets will have a deleterious effect on human health, at least until we (our descendants) adapt (if it's even possible.)
This title is a bit imprecise. They detected four planets with lower bound on their masses to be down to 1.7 Earth masses. Because these planets don't transit, there are no direct measurements from their radius. They can use mass-radius relations to infer the radius of these planets, but the key finding is their masses (actually lower bounds on their masses).
Can you say they _don't_ transit? They say the planets were detected by analyzing star wobbles, which doesn't necessarily mean that the planets don't transit, just that it's not how they were detected.
However, we have a good prior on the inclination of these planets, because we know the inclination of the dust disk around the star (https://www.scientificamerican.com/article/tau-ceti-s-dust-b...), and it is likely the planets are at a similar inclination. Because the disk isn't edge on, the planets also likely aren't, and won't transit.