Recent comments in /f/askscience

ElderOldDog t1_jclj20g wrote

Reply to Would A Brown Dwarf Cause An Orbiting Object To Cool? by Masterpiece-666

Having been made curious about 'brown dwarfs' (aka 'short Lamanites [you have to be mormon to get it...]), I asked Google and found one interesting item that I hope you haven't overlooked:  All the brown dwarf stars found to date are in binary systems.

But I found nothing regarding the possibility of the binary system having two brown dwarfs...

If you need a non-judgmental 'early reader,' feel free to reach out to me, a 78-year-old literate Sci/fi fanatic.

7

KnoWanUKnow2 t1_jclfzmv wrote

Reply to If UV radiation is used to disinfect and sterilise things then why isn't everything the sun touches (your skin, the sidewalk etc) sterile? by Critwhoris

It does.

But mane-made light is more effective because it is more powerful. Our atmosphere blocks a lot of the sun's UV rays. Also organisms evolved with sunlight, so they have developed mechanisms to resist and repair the damage.

But enough sunlight will kill most microorganisms.

However, your skin has pores. Sidewalks have micro-fissures. There are places where microorganisms can hide from direct sunlight.

So the sun will deplete their numbers, but won't eradicate them.

62

eotfofylgg t1_jclfjlr wrote

Reply to comment by Alfred_The_Sartan in What makes one greenhouse gas stronger at trapping heat than another? by sand_eater

The atmosphere is full of wind, which keeps things pretty well mixed, at least in the troposphere.

In a hypothetical perfectly still atmosphere, the heavier molecules would tend to settle to the bottom. Even then, the air wouldn't be perfectly stratified like a layer cake, because there is enough thermal energy to mix the layers. But you would observe that, as the elevation increased, the concentration of heavier molecules dropped off faster than the concentration of lighter molecules.

1

Grindipo t1_jcld3tw wrote

Reply to comment by dangil in Energy can not dissappear or be created, only change form, right? Earth is blasted by the sun 24/7, where does the excess energy go, because I guess it doesn't stay here or we'd cook by mr_greenmash

Is it you, Lord Kelvin ?

The heat inside Earth comes from the radioactive decay of, well, radioactive elements inside.

It is true that the accretion of a planet releases a lot af heat, but without the radioactivity, the Earth would have cooled in less than a billion year.

2

Foxs-In-A-Trenchcoat t1_jclazfo wrote

Reply to If UV radiation is used to disinfect and sterilise things then why isn't everything the sun touches (your skin, the sidewalk etc) sterile? by Critwhoris

UV irradiation works by ripping apart DNA, which then kills microbes. This is also how it gives you skin cancer. Organisms have evolved ways to prevent and repair this DNA damage with varying amounts of efficiency. A bacteria called Deinococcus radiodurans is the most efficient.

10