New answers tagged

4

Using the same methodology I used in my answer to How Big Can a Habitable Planet Get Before Its Gravity is More Than 0.8 m/s² above Earth's 9.81 m/s²? I've made the following table. The last line is data for Earth. A planet that has a radius that is 0.62 the Earth radius and 0.3836 the mass of the Earth will have a surface gravity very close to $g$ and an ...


2

This answer will be divided into several parts. In this story, I would want two planets that are both large enough to support life, but don't have to be the same or close in size. Do you want your planets to be the right size to support carbon-based liquid water using life in general, or the more specifica case of humans beings (and other oxygen breathers) ...


0

Your nights would either always have a moon, or never have a moon. Binary planets will inevitably become tidally locked. https://phys.org/news/2014-12-binary-terrestrial-planets.html This configuration, termed a terrestrial binary planetary system, would necessarily evolve into a state where the two bodies are tidally locked (with orbital period being ...


2

It depends on the albedo of the planets (how much light it reflects). For example, Mercury has an albedo of 0.06, which means it reflects only 6% of the light that hits it, whereas Venus has an albedo of 0.75.


1

It's certainly difficult to find information on the locations of individual stars in globular clusters, given that none are in our stellar neighborhood - which is expected, as they occupy the galactic halo. Messier 4 is believed to be the closest globular cluster to Earth, and while its distance is disputed, a value of ~7200 light-years seems to be commonly ...


1

Do you really need a spatial map of a real star cluster for your story? Stars tend to orbit and move around so the map would have to include hundreds of thousands of stars, each with a three dimensional spatial co-ordinates as well as velocities and accelerations in 3D as the picture would change over time. This might not be exactly what you want but it's a ...


0

Stars are big. Really big. But leaving that aside, let's suppose you have enough of the right material from somewhere and want a planet with a crust, built on/from the same body that was previously a star, without going through "make something new out of gas clouds". It wont happen. A brown dwarf is the smallest main-sequence star category, and is ...


0

First to answer your stated question: Yes. But not as you envision it, with the planetary matter settling on the star remnant to form a crust. If enough matter stayed nearby, and coalesced, it would just form a new smaller star. But typically when a star dies in glory, it sweeps any and all planetary system it used to have before the winds of its demise. The ...


0

There are believed to be hundreds of billions of free floating planets in our galaxy, if not trillions. You don’t need to invoke any special or unusual circumstances for them to be formed; the ejection of one or more planets from a new solar system due to their gravitational interactions is perfectly normal


0

A star never just 'disappears'. From what we understand as of now, dead stars usually end up as neutron stars or black holes or explode into a supernova. When they end up in a neutron star or a black hole, they will just swallow the planets up. When they can end up in a supernova, they can (depending on their mass and radius) end up as supernovas and ...


4

Our Sun, and the solar system with it, is a third generation star, meaning that it formed with the remains of one or more exploded stars which formed with the remains of one or more stars formed at the beginning of the Universe. This has been determined by the type of elements contained in the Sun and requires at least two generations of star to be ...


4

Short version We believe neutron stars cool down very fast, compared to other stellar remnants, so that they are only "hot" for a comparatively short time. Therefore despite their novel phase/ state, their magnetic/ superfluidity/ possible reheating phenomenae, and possible infalling material, most neutron stars quickly become cold, dead, tiny, ...


3

Searching for "neutron star appearance" you would have found this very similar question, from where I quote the answers: A neutron star is very small for an astronomical object. 15–20 km diameter, this is like a medium size asteroid. From a distance larger than 50 thousand kilometres (in astronomical terms nothing, 1/8 Earth-Moon distance) it ...


0

I'm afraid you want to see this article. https://www.astrobio.net/meteoritescomets-and-asteroids/the-habitable-edge-of-exomoons/ To summarize, it says that the need for the moon to be so close to the red dwarf star to have water and all the tidal forces would make such a moon uninhabitable. Sorry, I thought a habitable moon around a red dwarf was an ...


3

It would be fine if you arrange the orbits properly. This system wouldn't necessarily be problematic if you can maintain stability via particular orbital resonances. We've discovered numerous compact systems whose stability is believed to be maintained on long timescales in this manner. Kepler-90 is a great example of a compact system kept in place by ...


3

Would having a single gas giant in such place as the middle of the habitable zone cause too much of an orbital havoc for there to be stability on the system? Pretty much yes, unless the habitable zone is really extended to that the perturbations induced by the gas giant can be negligible. This is what happened in our solar system in the asteroid belt The ...


9

I'm surprised no one has given this a more direct quantitative treatment, so here goes. The perceived brightness at the Earth's surface is related to illuminance, or luminous flux per unit area. Direct sunlight at noon is about 100,000 lux. Illuminance from a source follows the inverse square law: it is inversely proportional to the square of the distance to ...


30

You would have a sky filled with 101 Venuses The apparent magnitude of these stars would be just a bit brighter than Venus at its best, less than 10% brighter. Of course, they would appear in the day, and twilight, and in the darkest night. The nighttime view would be quite spectacular, about similar to looking at the sky over JFK airport during a baggage ...


34

Will the nights be brighter? Will these stars be visible at day? Any interesting deviations from the typical sky? Nope, no big difference. First of all, take a look at this chart showing how the Sun look like when seen from various bodies in our solar system 68 AU is still 0.1% of 1 light year, so every single star won't stand out that much. Below another ...


Top 50 recent answers are included