Recent comments in /f/space

fdeslandes t1_j68hahs wrote

Reply to If you could instantaneously place a space telescope at any desired distance (LYs), from any planet/galaxy etc., where would it be and what would you be documenting? And for what purpose? by kennyarsen

Too bad the closest black hole is thousands of light years away, because even at tens of light years away, decades of latency would have been worth it to put a telescope near the black hole and not only observe it, but use it as a lens to get the best telescope we could ever hope to have.

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Taalnazi t1_j68fnr0 wrote

Reply to comment by John-the-cool-guy in If you could instantaneously place a space telescope at any desired distance (LYs), from any planet/galaxy etc., where would it be and what would you be documenting? And for what purpose? by kennyarsen

Or KOI-4878.01.

Likely to be in the habitable zone. No idea if it has got a large moon and a Jupiter in the outskirts, though. Star is also an F-type, meaning it stays stable for only 2-4 billion years, rather than our G-type Sun's 10 billion (though Earth will be in the habitable zone of it for only 5.5 billion years).

Kepler-90 similarly has an F-type star, but it has the same amount of planets.

There is "habitable", which you should understand as "habitable for life" (so even only for microbacteria-like life), and there is "Earth analog", which is what laymen are actually looking for.

• A stable star (G, K-type main sequence; or a M-type. Either way, the star's luminosity variability should be "quiet", ie. no more than 0.5%; our sun has 0.1%). The star should be older than 500 milion years. For alien life that's not just microbes, I personally think at least 3 billion, but not more than 6 billion years old, would be a safe bet.

• Eccentricity below 0.20 (for comparison, Earth has 0.0167, Mars 0.0934, and Mercury 0.2056). This is assuming a 24-hr orbit, 365 days of year, with a star like our sun. Higher, and water can remain liquid only temporary.

• A longer period, about 100 days at least (this is just my opinion). While I think shorter cycles could also be possible, I think it'd be hard for life to adapt to short and quick seasons. Perhaps it'd be adapted like a sleep cycle.

• Should be in the zone where the solvent is mainly liquid (ie; oceans; thus, habitable zone); or be a moon whose atmosphere is protected and whose surface is warmed, both by the host planet's magnetic field. Where this habitable zone starts and ends, depends on the star. For a G2V star like our sun, with water as solvent, it's about 0.8-1.15 AU (120-172 million km) away from the star.

• Have a relatively high density (which points to an iron core and thus likely a magnetic field).

• Equilibrium temperature combined with its atmospheric pressure needs to provide for a liquid solvent (ie. ocean) of water, methane, or ammonia.

• The planet should be below 10 Earth masses and between 0.8 and 2.5 Earth radii. Note that planets like these, if they have a radius leaning close to 2 or more, may be easily entered but hard to leave by rockets. Bigger and the atmosphere will be too dense. Smaller and it cannot hold onto its magnetic field for long, and thus also not its atmosphere.

• A large gas giant further away, to redirect meteors and comets away, also helps.

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nicuramar t1_j689lu5 wrote

Reply to comment by Feeling_Percentage_9 in If you could instantaneously place a space telescope at any desired distance (LYs), from any planet/galaxy etc., where would it be and what would you be documenting? And for what purpose? by kennyarsen

That’s not exactly correct? First, you’ll still be in orbit around something. It’s just some local gravity that cancels. Second, an orbit is another point where you can stay indefinitely. “Location” is pretty relative.

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Feeling_Percentage_9 t1_j6899v7 wrote

Reply to comment by nicuramar in If you could instantaneously place a space telescope at any desired distance (LYs), from any planet/galaxy etc., where would it be and what would you be documenting? And for what purpose? by kennyarsen

Lagrange points are where there is NEUTRAL gravity is when the gravitational forces from different objects cancel each other out, thus no pull in any direction. An object can be in this location indefinitely without the need of thrusters.

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saulbellow1 t1_j6876zc wrote

Reply to If you could instantaneously place a space telescope at any desired distance (LYs), from any planet/galaxy etc., where would it be and what would you be documenting? And for what purpose? by kennyarsen

A point far enough away that light reaches it from the Cretaceous era, I’ll turn the scope on earth and document some Dinos in action

And then move it closer to earth for every mysterious time period: pyramids being built? in 4K resolution. Jesus on the Mount? With Crystal clear sound. Advanced civilizations of south and Central America before the Spanish conquistadors wiped them out? I’m getting enough footage for a moving biopic of Quetzalcoatl. Anything we have questions about regarding our history will be answered with my Time Machine telescope

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nicuramar t1_j68311l wrote

Reply to comment by SailingNaked in If you could instantaneously place a space telescope at any desired distance (LYs), from any planet/galaxy etc., where would it be and what would you be documenting? And for what purpose? by kennyarsen

> That is where OP and you are wrong, and that’s their point I wanted to clarify. The words are interchangeable

Well, it’s just arguing semantics. Since I know how it actually works, irrespective of what you or I wish to call it, I am not going to address the rest of the comment.

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