The sky is everything that lies above the surface of the Earth, including the atmosphere and outer space.
In the field of astronomy, the sky is also called the celestial sphere. This is an abstract sphere, concentric to the Earth, on which the Sun, Moon, planets, and stars appear to be drifting. The celestial sphere is conventionally divided into designated areas called constellations.
Usually, the term sky informally refers to a perspective from the Earth's surface; however, the meaning and usage can vary. An observer on the surface of the Earth can see a small part of the sky, which resembles a dome (sometimes called the sky bowl) appearing flatter during the day than at night. In some cases, such as in discussing the weather, the sky refers to only the lower, denser layers of the atmosphere.
The daytime sky appears blue because air molecules scatter shorter wavelengths of sunlight more than longer ones (redder light). The night sky appears to be a mostly dark surface or region spangled with stars. The Sun and sometimes the Moon are visible in the daytime sky unless obscured by clouds. At night, the Moon, planets, and stars are similarly visible in the sky.
Some of the natural phenomena seen in the sky are clouds, rainbows, and aurorae. Lightning and precipitation are also visible in the sky. Certain birds and insects, as well as human inventions like aircraft and kites, can fly in the sky. Due to human activities, smog during the day and light pollution during the night are often seen above large cities.
if i shoot a bullet to the sky and then the bullet falls to the ground at the same point that I am standing...will i die? the bullet's start velocity should be same as final velocity...from the equation E=1/2mv^2 shows that the energy when i start shooting = energy when the bullet falls to the...
I have a basic question regarding black body cooling. Suppose a person at sea level on a clear night, were to use a hot water solar panel which is a good black body, and contain it in a box in a vacuum with a 'window' that was very good at transmission of long wave ir 'looking' only at the sky...
If I rember correctly, the sky seems more blue, when you look through a pair of sunglasses with orange glass.
Why is that ?
can anyone help out here.
Orange glass is orange because it absorbs some of the blue light - but then the sky should be less blue - right ?
-ZeroGravity
This happened about a month ago. I was looking out my window at the sky at about 10 o'clock at night. I was looking West and I noticed an orange light. It hadn't been there moments earlier. About thirty seconds later it was gone. I figured it might have been a plane, but it didn't move. It just...
The night sky in my area does seem clearer of late, even with the multi giga watt street/road lights shining bright many stars can be seen, is this true across the uk?
Hi! I just saw something very unusual in the Boston sky today at 4:00 PM. Yes, in the middle of daylight.
It looked a lot like a star and it was almost straight up. It then slowly moved roughly from west to east and went maybe 45 degrees in 5-6 minutes. That would give whatever it is an...
I have done a little research on the internet and I would like to ask my concept is correct or not.
1) Sky is blue
As the effect of rayleigh scattering is more effective for shorter wavelength, blue light scatter more than others (e.g. red). Furthermore, our eyes are more sensitive to blue...
Suppose it's a very clear night. You take a laser-pointer, and briefly allow it to "shine" into the sky.
Will the photons emitted from your laser actually make it millions of miles into space? Or will they somehow "dissipate" and not make it that far?
It would be very cool to think that...
I want to learn about the night sky and the data about constilation so when I look at the sky I could figure out which star belongs to (x) constilation and its relative position with others...
Is there any link which can help me out?
Thanks for your help
Is there any end to the sky?Why do we think that if the universe is expanding then it had exploded from a single object?Why not think there is some extra force outside this universe making it expand?Can anybody imagine what the end of the sky or space would be like(may be a beginning of a space...
Hi,
I'm curious about one thing. Suppose the universe will end in a Big Rip. Then since the universe will be accelerating at a very fast rate, could it be that the sky will look redder and redder towards the Big Rip?
What IS this?
Yesterday I was driving home from school when I saw that in the clouds there was what seemed to look like a portion of a rainbow :confused: :confused:
I thought it was weird, so I took a picture of it while driving, with my cell phone, so it's not the best quality :redface...
I don't know if anyone would be interested, but for some time the BBC have been broadcasting The Sky At Night over the web for anyone with Real Player. This show is broadcast once a month in the UK (don't know if its on the world service either) and is an astronomy & astro physics magazine...
Why doesn't the sky crush us all??
I'm sure I've thought this through before but after an afternoon wondering I need to ask:
Why is it that the billions of tons of air above us doesn't crush us?
Thanks for the help!
It started out very slow, and then end in a fury of outstanding pictures. So again, congratulations to everyone who participated. This is going to turn out to be another difficult contest to pick.
1. ZapperZ
http://img351.imageshack.us/img351/7945/img38639zy.jpg
2. Moonbear...
Fire In The Sky
With the US Independence Day coming up on the 4th of July, what more appropriate theme to have right now than... FIREWORKS!
All your pictures must feature fireworks. It does not, however, include unexploded fireworks (i.e. pictures of fireworks in a package in some store do...
More "Things in the Sky"
RULES:
1. Each person may attempt to answer only 1 question. If there are unanswered questions in say, two days, I'll announce a free-for-all, whence everyone may go for all the remaining ones.
2. You may Google all but the last question. Some of the questions are...
"Things in the sky" quiz
All right boys and girls, here's an easy quiz to get started. Let's sharpen up those pointy heads.
Please do not google the answers, these are easy enough and it's multiple choice. If I could get them right without googling, so can you.
Please answer in...
http://antwrp.gsfc.nasa.gov/apod/ap060531.html
GLAST means "gammaray large area space telescope"
http://glast.gsfc.nasa.gov/public/
and it is scheduled to fly in 2007
this is a 55 frame animation of the full sky
you can see the Milkyway snaking across, roughly east-west.
there are...
Consider the possibility that the universe isn't infinite exactly, but that it just wraps around (like the surface of a sphere) giving the impression of being infinitely large. If this is the case then some light emitted by a star, which is not absorved, may have the chance of going around the...
there is a terrible problem with me , my younger brother ask me a question that I had tried my best to think but it's too difficult for me , he say if in fact it happens , we sit on a chair anh wait to die ?:smile:
There is a country has 3 cities , the true city , lie city and...
I've often observed the sky in the late evening and it was dark. But on cloudy days, the sky is actually bright. The housetops appear dark compared to the sky. And the clouds appear in a dark red tone
Anyone has an explanation for this? Does the light come from earth, from the moon or from the...
The sky is blue because the white light is diffused by the light particles, which scatter out the blue end of the spectrum, hense a blue sky. In the afternoon, it is often red or orange, because the light has to travel much longer through the atmosphere, scattering out the red end of the...
A skydiver jumps from an airplane and descends at a constant velocity of 2m/s. The mass of the skydiver and his equipment is 70kg. Calculate the magnitude of the air's frictional force acting on the skydiver and his equipment.
F = 70kg x 9,8N/kg = 686N
I'm lost
(a) What is the acceleration of two falling sky divers (mass 102.0 kg including parachute) when the upward force of air resistance is equal to one-fourth of their weight?
________ m/s2 (downward)
(b) After popping open the parachute, the divers descend leisurely to the ground at constant...
What do you guys think about when you look at the sky, sun, stars, other heavenly bodies? I think about lots of things: various connections to legend, literature, and science; what's out there that I can't see; which stars are still there; 'the stage is too big for the drama'; someone or...
i saw summin last night it whoosshed past, i was just looking out the window at the stars it was a really clear night and then i saw it i don't kno what it was a comet? or a rock or something falling to earth. but it made me feel better, i was feeling upset before. around quarter to 9.
I saw a star just yesterday night about southwest in the sky, and when viewed through my telescope it was flashing red and blue.It was no plane for it was there all night.Is this caused by the atmosphere?If not what is it?
I live in a pretty well lighted neighborhood.Lately the entire neighborhoods power has been going out. It makes it completely black outside.I saw a red star or something very low to the horizon northeast in the sky?anyone know what that may be?I also saw a star that was flickering all sorts of...
This paper just came out this month
http://www.arxiv.org/abs/astro-ph/0508047/
On the large-angle anomalies of the microwave sky
C. J. Copi (1), D. Huterer (2), D. J. Schwarz (3), G. D. Starkman (1) ((1) Case Western Reserve University, (2) University of Chicago, (3) Universitat...
The stars in the sky are all emitting their own light. The light is reflected for infinitely many times and part of the light energy will be stored in objects. But why is the sky so dark? Why is it not bright?
I recently came across an argument that stated that Earth's nighttime view pretty much always faces the outer rim of our galaxy, while the day time view is facing right towards the center, which of course we don't see due to sunlight. There was refrenced a few indian tribes in s.america who trek...
Dear friends,
<<A cable of constant mass per unit length (p) points straight up hovering over a point on the Equator. How long has to be the cable?>>
I believe there's a mistake in my answer and I need somebody to give me a hint. What I've done is: integrate dF(gravitational force) over...
Source; The Guardian - London, UK
http://www.guardian.co.uk/arts/news/story/0,11711,1427600,00.html
03-01-05
Ancient Sky Map Or Fake? German Experts Row Over Star Disc
Luke Harding in Berlin
The Guardian
quote:"One of Germany's most acclaimed archaeological finds - a 3,600-...
Average luminosity of night sky vs frequency...
What is the average luminosity of the night sky in all observable wavelengths, from the shortest down to the longest? Are there estimations/approximations anywhere of average luminosity plotted against wavelength? Are there links to papers that...
Hello, does anyone know of any good resources for solar path data? Like what angle in the sky the sun is at for different parts of the year.
Thanks,
AL
Recently, several groups have endeavored to experimentally map the large-scale structure of the Universe with the Sloan Survey being the most ambitious.
At the same time, we've been able to map the cosmic microwave background to 10^-6 degrees. I believe these two maps agree but I'm confused...
Ok, I'm trying to help my son with this test question he got wrong. He is in a basic high school physics class and I have virtually no experience with physics. The book and classroom handouts have nothing that completely explains this question. Any help and explanation would be most...
When a car is travlling at constant speed, we say that the forward force is equal to the frictional force. How is that possible? Shouldnt the car be stationary?
Samething with sky divers, when the air resistance balances with their weight, how is it possible that they still move downwards...
I've never been able to get an answer as to why is the sky blue yet the light that reaches the Earth white. I've been told that the Nitrogen in the Earth's atmosphere refracts the white light coming from the sun in a way that makes blue more visible. That's fine, however, what I can't...
I'm not sure which sub-forums this should go in...
Does the shade of blue that the sky appears to be change at all at differing lattitudes on Earth?
What about different altitudes?
If so, how much?
Any links to specific info?
Thanks for any input you have.