when we r in space, what do we see, brightness or darkness?

Question

Like facing sun on earth, it is bright all around. what about when we go to space and we are exposed to sun? Is that brighter and hotter than being on earth?

Answer 1

The Sun is a *lot* brighter once you get above the Earths atmosphere. And there's a lot more radiation at a lot of wavelengths that are pretty much all absorbed by the atmosphere.

As far as 'dark' is concerned, anywhere you look that doesn't have something (a distant star, etc.) that emits light, or something that reflects light (such as the moon), you'll 'see' blackness.

As far as 'temperature' is concerned, space has no temperature. But the side of you that's facing the Sun is absorbing a lot of energy (several killowatts per square meter) and the side facing away from the Sun is looking at an infinite heatsink with an equivalent black-body temperature of a couple of tenths of a Kelvin.

The truly impressive engineering on the Hubble isn't the telescope, it's the frame and support system that encloses the instrument. Every time the Hubble crosses the terminus (the portion of its orbit that takes it into or out of the Earths shadow) the temperature of the structure changes by several hundred °C so there's a lot of thermal expansion/contraction going on. But it *still* has to maintain the instrument pointing in a particular direction to within a few µradians to yield images that are distortion free. Quite a feat.

HTH

Doug

Answer 2

There is a law of light called "the inverse square law", which basically says that if you are at a distance of X from a light source and the intensity is Y, then you will get these values for X = ...


X = 1 --> Y/12 = Y/1 (per square meter!),
X = 2 --> Y/22 = Y/4, (X = 2 means twice the distance)
X = 3 --> Y/32 = Y/9, (X = 3 means three times the distance) and so on...


So, If we say that the orbit of Mercury takes it 50 million km away from the sun, on average, 100 million for Venus then the amount of light per square meter will be 1/4th on Venus than on Mercury, because it is roughly twice as far away as Mercury.
As you can see, the same "amount" of light will spread over a larger and larger area as you get further away, which means less and less photons hit each square meter.

I could help you to calculate the initial intensity of Y, but it requires some calculations and the end result may not be very helpful. So I'll go ahead and give you factors of light that roughly describe how many times the light of the sun appears dimmer...


Earth = 1, orbiting 150 million km away Jupiter:

Mars: 2,35 times fainter than earth, (230/150)2
Jupiter: 27 times fainter, (780/150)2
Saturn: 91 times fainter, (1430/150)2
Uranus: 366 times fainter, (2870/150)2
Neptune: 900 times fainter, (4500/150)2
Pluto: 1547 times fainter, (5900/150)2

And of course:

Venus: 2.25 times brighter, 1/(100/150)2
Mercury: 9 times brighter, 1/(50/150)2


As you can see the light from the sun at the outer solar system is very dim. When you see paintings of pluto and such, the intensity of the light has been magnifyed. Why? Because the artists usually want to illustrate what the surface looks like, but what would they be able to show if the light source would be as dim as it is? A black sphere?

In empty space, like in between galaxies or stars, there is virtually no ambient light and the light from the stars is too dim, so a side of an object that doesnt receive any light will be pitch black. But if you are in a nebula there is much dust, or other elements that contribute to some ambient light, which could provide lighting on parts of an object that would be black else, but I believe even that light may be dim. Keep in mind though, the pictures we see from the Hubble space telescope (and other telescopes) have been exposed to the light for minutes or hours, because the objects are faint.

btw,The sun has an apparent magnitude* of -26,73 and the full moon has an apparent magntitude of -12.6, so the difference is 14,13 in terms of magnitude. Which makes the sun appear 450 000 times (2,512^14,13) brighter than the full moon, from just outside the atmosphere. That is all I can say, really. This data doesnt give me a picture in my head of how bright it is.


* Apparent magnitude is a measurement of a celestial objects brightness, it depends on the real (absolute) magnitude of the object, the distance to it, and any gas or other interstellar material that blocks some of the light.

Answer 3

The Sun seen from space is the same as when seen from Earth. Not hotter and not cooler; not brighter and not dimmer. But the lack of air makes a difference. There can be no cooling breeze, so anything in direct sunlight gets really hot, like a car parked in direct sunlight on a hot summer day. And when you are in the shade of something, like the night side of a planet or the side of a space craft facing away from the Sun, there is no warm air around to keep the heat in, so it gets colder than the south pole in winter!

Answer 4

Without an atmosphere, heat can only travel as electromagnetic radiation. Therefore, brightness will only be observed directly emanating from a source of light, be it the sun, stars, or light reflecting off another object, and travelling in a straight line only. In earth orbit, it is hotter when exposed to the sun than being on earth, because there is no atmosphere to shield you. In shadow however, it is very much colder and darker. Far from the sun, the temperature falls to only a couple of degrees above absolute zero (-273 celcius).

Answer 5

Your eyes sense light but your mind can determine the lack of it. Your brain will interpret lighted objects and degree of brightness or lack of it.

Answer 6

no you see both light and dark and its colder the higher you get