Taalnazi

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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Taalnazi t1_j2duhrm wrote

Reply to comment by rootofallworlds in What is the timeline of star death? by jfgallay

Thanks. Hmm... and so far, no star has been discovered yet in their carbon-burning or more advanced-burning phase? Or do carbon stars fall under this?

There are supernovas we observe, sure, but do we know when we look at the very last stages before it? Can we detect the 600-or-less-years phases?

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Taalnazi t1_izsw942 wrote

Reply to comment by SansSanctity in [OC] Yearly Average Temperature in the UK, 1884 - 2021 by PieChartPirate

Well, for that you have to thank politicians who were deeeeep in the oil and gas pockets. They did nothing to construct clean energy stuff.

So now we are paying the price for that. No one of us wanted this, except for the greedy companies and some politicians.

You can wear thermo clothing. You can drive an electric car or bicycle and demand better infrastructure and public transport. Plenty of opportunities.

Not doing anything and crying about not having enough gas, which itself harms the climate, is not the solution.

The US has decreased some emissions, but far too few and little. It needs to go to zero.

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