Exoplanet Stats

[Helio]

There will never be a step improvement any greater then the second Vanguard back in 1957, when we avenged the failure of Vanguard I and finally put something into orbit. I was 5 years old and remember the fear in the adults because the Soviets had bested us. and then the overwhelming relief when we made it.

I was just 4 but I do recall, a few year later, the ongoing tension caused by Sputnik. I think I looked up one night hoping to see Sputnik, which had caused all the fuss. [They didn't mention it wasn't still up there. ]

The Moon landing I would still rate higher, likely because the Sputnik tension was not the latest and greatest threat from the Soviets.

Hopefully a Mars landing will come when there are very little world tensions. Wishful thinking, I suppose.

 

[billslugg]

Actually:
Sputnik went up 4 Oct 57
The dramatic US failure was Vanguard TV3 on 3 Nov 57.
Our first successful orbiter was Explorer 1 on 1 Feb 58
Vanguard 1 was 17 Mar 58
Vanguard 2 on 17 Feb 59

 

[ImmortalMelvz]

There's another milestone for America, the Golden Dome, what can you say about that?

 

[COLGeek]

There's another milestone for America, the Golden Dome, what can you say about that?

See this article and discussion: https://forums.space.com/threads/u-...lion-golden-dome-space-defense-program.71518/

 

[Helio]

Here's another way to present the HZ (Habitable Zone) planets. This shows how many of three different size ranges (too small, too large, just right) and their relative position in the HZ with bright green being in the more likely (conservative) zone.

 

[ImmortalMelvz]

It's true, every star has a habitable planet!

 

[Catastrophe]

It's true, every star has a habitable planet!

Habitable by what?

Unless you are defining what can do the inhabiting very widely indeed, most definitely
to include the simplest microorganisms, and also to include planets which have been subjected to the most extensive modifications, the above is untrue.

It is certainly not the case, that every star has a habitable (by humans) planet.

It would be a small improvement, if you modified the statement to include "every star has a habitable planet" "at some point in its history", but this is still not the case.

Cat

 

[Catastrophe]

Just to flesh it out a little, Google provided the following.

First, what proportion of stars are like our Sun?

Approximately 8-10% of stars in the Milky Way galaxy are considered "solar-type" stars, meaning they are similar to our Sun in terms of size, temperature, and other characteristics. These are typically classified as G-type main sequence stars.

Of these, the following might be considered habitable:

Approximately 22% of stars similar to our Sun are estimated to have Earth-sized planets within their habitable zones. This means that around one in five sun-like stars could potentially harbor habitable planets. While not all of these planets will be truly habitable, this statistic suggests a significant number of potentially habitable worlds exist in our galaxy.

So, around 2% of planets in our galaxy might be habitable.

This can only be considered as very approximate.

Directly observing planets outside the Milky Way (extragalactic planets) is incredibly challenging due to vast distances

But, don't worry. There are plenty of stars in our galaxy.

It is estimated that the Milky Way galaxy contains between 100 and 400 billion stars, and most of these stars are likely to have planets orbiting them

Cat

 

[Helio]

The data shows < 0.2% of G-type stars have exoplanets that are both earth-sized and in their HZ. This number could increase as many exoplanets still have unknown radii.

So if G-type stars are about 10% of all stars, then we have < 0.02% of all stars have exoplanets in their HZ. Of course, K and F stars may also prove fruitful with their exos in their HZ, so this will improve the odds.

See post #189