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.
I just watched this http://www.youtube.com/watch?v=TFwtJC9_dXs" that said it's because the universe has a finite existence and the light from most of the stars hasn't reached us yet and this would be an argument against an infinitely old universe. Is this correct?
I understand that there are different meteor showers at different times of year, and that they are named for the constellation from which the meteors seems to come from (to an Earth-based observer). Does the point of "exit" for arbitrary meteors all year follow a pattern or a great circle on the...
So basically I want to write some code in Python to project the movement of the moon and sun across the night sky. Basically, I need a projection such that the shape of the moon won't change as it moves in the sky (especially when it's near the horizon) - the objects have to look fairly good...
Hi
I want to know how astronomers count the number of stars (or any other celestial object for that matter) in the sky.
Will they take a photograph and do some signal processing like counting the number of brightest spots? Is it possible to count accurately since there are billions and...
1. What are two examples of physics found in Apollo 13 or October Sky Physics
3. When they slingshot around the moon and in October Sky when they do the projectile and when the mine caves in. I need one more for Apollo 13..with explanation please
Ok, my brother & I were trying to work this out.
Without directly knowing the angles is it possible to work out how far away a plane is in the sky?
For example, a boeing 747 is about 70m long. It appeared to be about 0.001m holding out a ruler about 80cm from my eye.
I look forward to...
Is there a 2010 sky almanac on line?
Hello. Is there any on-line resource that I can obtain a nice star almanac like the one in the January issue of Sky and Telescope? I realize I can buy it for $6.00 through Sky and Telescope but does anyone know if I find a similar one on the web that I can...
Homework Statement
Basically, i was told to describe the physics involved with a person who just happens to be falling out the sky...However, I'm a bit overwhelmed as to where i should start off
Human mass: 54kg
Earth's gravity: 9.8m/s^2
Air resistance:?perhaps negligible or would that...
Hello PF
I'm hoping someone can answer this for me.
I am in Ottawa, Canada and right now it is almost 2 am. I am about to go to sleep but can't help to notice why the sky is so unusually bright. It is a light peachy color. I can see the grass outside my house without any lights, it is...
I'm so over my head that I don't even know how to ask this, but here goes...
The accelerometer in my device (an iPhone) gives an x,y,z vector that points to Earth. I'm using these values to determine the angle of the device relative to the horizon. Visualize a user aiming the device at a...
When I was very young I got up out of bed, in the middle of the night, and looked out the window and saw this big bright red ball of light in the sky. I'm 58 now so it is very hard to remember but I have never seen it again and I have never found anything reported that looked like it. It flashed...
Hi all,
I need to get an aitoff all sky flux map. I have flux given by an equation that depends on different latitudes and longitudes.
I also know how to get aitoff projection in maple 12:
My problem is that I do not know how to superimpose my flux values on this aitoff map to get an...
Homework Statement
Members of a sky diving club were given the following data to use in planning their jumps. In the table attached, d represents the distance fallen from the rest by a sky diver in a "free-fall stable spread position" verses the time of the fall.Analyze bot qualitatively and...
Hi I'm writing a story and I need to figure out what color the sky is on a planet orbiting Zeta Tucanae that has close to the same atmosphere as earth.
just so you know Zeta Tucanae's Spectrum is F9V and Color Index is 0.576
It would be great if you can tell me how to find the color...
What color is the sky on extra-solar planet?
Hi I'm writing a story and I need to figure out what color the sky is on a planet orbiting Zeta Tucanae that has close to the same atmosphere as earth.
just so you know Zeta Tucanae's Spectrum is F9V and Color Index is 0.576
It would be...
Hello,
Sorry if this is not the right place but I'm trying to find this for days now...
I'm trying to find a working formula to determine the position (r.asc/decl) of a star at any given time and for a specific location on earth.
So the parameter would be:
R. Asc. of the star...
Ok, this is kind of a stupid question, but I was curious... If I lived on a planet that had an atmosphere, but a red sun, what color would the sky be? If I lived on a planet with two suns, one red, and one blue, what color would the sky be? I know some light is absorbed into the atmosphere and...
So I just got my dads old telescope out, cleaned it, and installed new motors and cleaned the primary and secondary mirrors, and it's ready for use! It's a reflector with a 4-3/8" primary mirror, and I wonder: what can I see with this thing (besides the moon, obviously)? I know this is a super...
Firstly, sorry if this is a stupid question but I was just wondering if there's a way I can tell if the night sky is observable where I'm living, Dubai. I really want to get a telescope but it'll be a waste if I can't even use it here.
Where I live, I wouldn't say that there's too much...
Have you ever seen three suns in the sky, if not then you have missed something... This is amazing phenomenon of nature... Check very very interesting article on this subject by clicking the link below.
http://www.risethemag.com/viewarticles.aspx?aid=186
http://www.google.com/sky/#latitude=-11.802834233547672&longitude=20.91796875&zoom=6&Spitzer=0.00&ChandraXO=0.00&Galex=0.00&IRAS=0.00&WMAP=0.00&Cassini=0.00&slide=2&mI=1&oI=0"
as the title indicates what is that thing near moon?
Hello all.
Forgive me, this has been piling up inside me for-- years. I tried a few other forums and no one can do anything but agree with me and express their equal ignorance. After reading quite a few post here, I think I may have found a group with the knowledge to answer my question...
I've wondered about this for a while:
-the Milky Way which we are part of appears to be a white cloudish streak in the sky. I guess this is because the stars are so far away that it appears as a cloud of light?
-But I would assume that all the stars in the Milky Way, our own galazy, must...
An eagle is flying horizontally at 7.9 m/s with a fish in its claws. It accidentally drops the fish.
(a) How much time passes before the fish's speed doubles?
(b) How much additional time would be required for the fish's speed to double again?
Initial velocity in the x direction is...
Lets say that we have a very long, vertical, grounded, electric conductor planted at the equator (something similar with the "space tether" satellite, but here on Earth). Now we can consider that the electric wire is moving through Earths magnetic field with the Earths rotational speed at that...
There were two stars one above the other in the Western Sky just after sunset. I think they were planets. One could by Uranus but I am not sure what the other may be.
I am at:
lat=40.91666667
long=81.43333333
Can anyone help?
So the latest i read was that the sky is blue because that is the color of air, just like water is blue for the same reason. Now this short article i read also claimed that sunsets are red because of some property of light that causes it to show different colors when it transmits light as...
http://space.newscientist.com/channel/astronomy/cosmology/dn14546-biggest-3d-galaxy-map-to-probe-dark-energys-history.html
In this cosmic cacophony, one particular note was louder than the rest, and it survives to this day as a characteristic wavelength in the clustering of galaxies...
Is 500 jumps a lot? I couldn't find any numbers online. Is 500 a lot in a mere 3 years? For someone who just does it as a hobby? She claims she did this in her teens, in the 70's.
A friend of a friend has tossed this number off casually and I'm having a tough time believing it.
i am tuan anh, i am from vietnam
very happy when join this forums
i have one question
when i see the lightning in the sky i don't hear nothing in it
i don't understand why
please help me
thanks
Lets suppose I live in a planet that is located in the tip of a galaxy that is ubicated at the most distant point from our universe. What would I see if I look up to the sky at night(looking away from the center of my galaxy)?
Manuel.
One summer night in 2005 I was out on my roof with a couple of my friends, and the sky was perfectly clear. We could see thousands of stars, it was amazing. We were in the countryside far away from any city lights.
Well, the entire night we were just star gazing and every 5 minutes we...
Huge filaments of dark matter have been detected in a survey of thousands of distant galaxies. The discovery supports the idea that dark matter drove the formation of galaxies and larger cosmic structures and resolves a discrepancy in previous studies about how much dark matter the universe...
Sorry if this is in the wrong part of the forum but I am a budding SciFi authro with many ideas. And I just wanted to check if one of my ideas is possible, and if not, how this effect could be best recreated.
I'm sure everyone has seen the Star Wars movies. Well if you remeber Star Wars...
Well part of it.
Disabled spy satellite threatens Earth
http://news.yahoo.com/s/ap/20080127/ap_on_go_ot/dead_satellite
BobG, what's up? Or down as the case may be.
Interesting to see if this has any impact on the launch of Atlantis.
If the sky could be any colour other than blue on a sunny cloudless day,
what colour would you want it to be? Do you think that we are all so used to the blue colour that we simply couldn't accept any other colour and would get depressed or at least very annoyed about it?
Just seen this on sky news, quite interesting. Unfortunately the article doesn't go into much detal.
http://news.sky.com/skynews/article/0,,30200-1301940,00.html
Do you think this is an effect of the night scopes? or is there some other phenominon going on here. I give the video 100% credability, as it seems several observers see the same thing... what are they seeing. Seems the brightest is over the biggest city.
Homework Statement
My physics teacher has given me a project to design some kind of device to allow landing from 5,000 feet without a parachute. So far we have been taught nothing but forces, velocity, acceleration, displacement, and vectors so I'm kind of at a loss. First step of the project...
I just saw a very bright meteor streak across the sky. I thought someone was shooting off fireworks until I remembered this..
http://www.griffithobs.org/skyreport.html
I want to go out and watch some more, but it's cold outside.
Homework Statement
A sky diver of mass 83.0 kg jumps from a slow-moving aircraft and reaches a terminal speed of 46.0 m/s.
(a) What is the acceleration of the sky diver when her speed is 30.0 m/s?
Homework Equations
R=-bv
mg-bv=ma
The Attempt at a Solution
since R is the...