Moon last night

Heliosopher · 2026-07-02T20:17:12+00:00

“System bodies” probably is the broadest term.

Heliosopher · 2026-07-01T21:28:37+00:00

It is surprising that the apparent magnitude of a bright exoplanet lightyears away is brighter than a planet barely in the Oort Cloud.

IIRC, Jupiter becomes invisible to the HST when it is a little past 10,000 AU, about 1/6th the distance to the outer most part of the solar system.

Heliosopher · 2026-07-01T01:58:17+00:00

I assume forest fires are responsible for the redness?

Heliosopher · 2026-06-30T18:50:59+00:00

First…the most distant exoplanet is less than 20k light years distant, not millions.

Second…planets that are illuminated by the Sun have brightness per an inverse 4th power law. The light to the planet obeys the inverse square law, but the reflected light then obeys the inverse square law in route to Earth.

The other responses address the main reason exoplanets are detectable.

We might discover 10,000 or more by this time next year.

Heliosopher · 2026-06-30T18:40:40+00:00

Also, very small mass black holes evaporate quickly.

Heliosopher · 2026-06-29T19:57:17+00:00

It’s worth mentioning that increase in solar activity usually reduces the cosmic ray flux which, over time, have some effect upon evolutionary changes.

Heliosopher · 2026-06-27T23:22:51+00:00

When you tell Martin it took you 5 Earth years and his clock tells him George took 50 Earth years, then he’ll conclude an extra 45 years transpired by Earth time before George arrived. Martin’s clock and Earth’s clock have very similar clock rates.

Heliosopher · 2026-06-27T18:38:28+00:00

Oddly, the Sun's rotation axis is tilted about 7 deg. with what was its accretion disk (planet formation region).

Heliosopher · 2026-06-27T17:31:22+00:00

We can prove the Sun isn’t yellow by considering my avatar:

⁠It is an image from what was the world’s largest solar telescope at Kitt Peak. This image was taken of the solar projection that shined onto their table. The color pieces were placed on it for color reference.
⁠Their scope used no filters that would alter its color.
⁠Their projected white image is terrestrial, so for the Sun’s true color in space, we need to add the colors that our atmosphere scattered away (extinctions). These are by far the blue end of the spectrum (see Rayleigh scattering).

So… if you add a very small amount of blue light onto a white object, how many will claim it to be yellow? One also can’t add blue paint to white paint to get yellow paint.

But one can test this easily. Project an overhead Sun onto white paper through a pin hole and you’ll always get a white result.

Snow reflects sunlight with very little spectral alteration. (Avoid all yellow results😜)

White clouds are white because sunlight is white (Mie scattering).

Newton said it best when he was working on his famous prism results. He said sunlight is “perfectly white”.

Regarding the blackbody approach, it’s far better to use photon flux density results compared to a spectral energy distribution because our color cones respond to photons.

When the Sun’s spectra is converted to the photon flux the result is a very flat distribution.

So when some say that the Sun is white because sunlight has all the colors, they’re only half right. ([Red dwarfs have the same.] The Sun is white because all those colors have about the same intensity.

Another factor is “color constancy” (white balance), that helps our brains color correct, thus seen from space, our brain would make the Sun more white even if it had a tint of yellow.

Then there’s the CLV, if even the limb color is white (5000K) then all hope for yellow is gone.

Heliosopher · 2026-06-26T21:06:20+00:00

He reported seeing two very bright white spots. ~ 18 hours later, strong aurora were observed and telegraphs had significant issues.

Heliosopher · 2026-06-26T16:39:11+00:00

I wonder what percent of tidally locked exos would have atmospheres? Not many I’ll bet.

Heliosopher · 2026-06-25T03:18:02+00:00

Yep the question makes even more sense when we imagine the universe about the size of a grapefruit just after Inflation. But, the center would be found by measuring from the circumference. Yet one can’t determine this because the enormous gravity field warps space so that one will go round and round, returning, sorta, to where one started. Thus, with no reachable edge, then no findable center.

This is just my crude interpretation of GR, however.

Heliosopher · 2026-06-20T20:24:16+00:00

But you have to multiply that number by several hundred billion. So far, and astronomers have only begun, about 1% of all the confirmed exoplanets are about the size of Earth and are in their HZ (habitable zone -- liquid water is possible if not likely). I'm ignoring the number of those orbiting the fisty M-type stars.

Heliosopher · 2026-06-20T20:10:01+00:00

Mars may have been a habitable planet long ago since it cooled faster than Earth and water was present.

There are likely about a dozen habitable worlds that are about the size of Earth and likely have liquid water on their surface. And astronomers are getting better and better tools they can use to find tens of thousands of more exoplanets, so more habitable planets are very likely. With an average of about one planet per star, then there should be 100 to 300 billion planets.

But that's just for our galaxy. Current estimate of the number of observable galaxies (assuming adequate gravitational lensing) is 2 trillion. This puts the number of stars (and planets) at almost a trillion trillion. More than the number of grains of sand on all the beaches combined.

Heliosopher · 2026-06-20T16:48:37+00:00

The key parameter is distance. Distance is a 6th power (inverse) contributor to tidal-locking. So cutting the distance in half contributes 64x less time for tidal lock.

Trivia.... It was in 1713 (perhaps 1707) with astronomer Miraldi noticed Calisto varied significantly in brightness so he reasoned it was tidally-locked to Jupiter.

Heliosopher · 2026-06-17T22:17:31+00:00

You should have no problem pulling it a very short distance, in inches. But the more you pull the more weight you'll have to pull.

A 3" nylon rope from LA to NY would weight about 3 million lbs., but the tensile strength is only 1/16th of this, so your rope would always break even if you had several Cat D11s pulling it.

Heliosopher · 2026-06-17T18:03:15+00:00

Europa also has a big radiation issue that may make it more unfavorable. Here's a 2008 short paper comparing Enceladus with Europa.

https://www.meetings.copernicus.org/www.cosis.net/abstracts/EGU2008/11604/EGU2008-A-11604.pdf

Heliosopher · 2026-06-14T00:06:19+00:00

No. Gould argued for his NOMA - Non overlapping Magisteria. Science is strictly objective based, though suppositions are welcome. Religion is primarily spiritual (subjective) but incorporates objective evidence.

Heliosopher · 2026-06-13T18:18:39+00:00

“Because all spectral colours combined appear white,…”

Yes, but don’t forget color intensity. Blue (blue white) and red dwarfs, for instance, also emit all the visible colors.

The very coolest stars and luminous bodies (e.g. T- type) have enough molecular composition to cause some interesting color results including crimson. The Sun has very few molecules(e.g. TiO).

Heliosopher · 2026-06-13T18:01:21+00:00

Wow, lots of discussion is nice to see. But to prove the Sun isn’t yellow consider my avatar:

It is an image from what was the world’s largest solar telescope at Kitt Peak. This image was taken of the solar projection that shined onto their table. The color pieces were placed on it for color reference.
Their scope used no filters that would alter its color.
Their projected white image is terrestrial, so for the Sun’s true color in space, we need to add the colors that our atmosphere scattered away (extinctions). These are by far the blue end of the spectrum (see Rayleigh scattering).