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.
Homework Statement
An arrow is fired upward with an initial speed of 38 m/s. What is it's maximum height? How long does it take to return to the ground? How high is it at 1.3 seconds? How high at 3.8 seconds?
Homework Equations
x = Vo*t + .5*a*t^2
y = .5gt^2
etc.
The Attempt at a...
Victoria, BC Canada
approx 23:00-23:20
Aug 12, 2012
Went to view the Perseid meteor shower with a friend. We were there about an hour watching when we noticed a small white light moving in the sky. At first we thought it was a small star but ruled it out after it moved a fair distance without...
http://s579.photobucket.com/albums/ss234/theranker24/Night%20Sky/
can someone look at them two photos i have linked on photobucket and tell me what it is that I am seeing.
and
Hi friends,
I am confuse in Rayleigh scattering formula.
It says that the intensity of the light corresponding to a wavelength in the scatterd light varies inversely as the fourth power of the wavelength.
Hence the blue light scatters more then red light. Hence the sky seems blue. But the...
Here are my two questions:
1) When i look up to a night sky, do i see mostly stars and galaxy's rather then planets?
Here is my logic: Since star is many many times more brighter then reflected light of planets i see brightest object and since we are looking form Earth planets and stars...
Hello Forum,
I understand how the primary rainbow is formed: dispersion by water droplets suspended in the air. A single internal reflection takes place. Red color (wavelength) emerges at about 42 degrees with respect to the observer...
but why is the sky below the primary rainbow not...
Wouldn't do me any good. I live in the middle of a major city, and, the last time I looked at the night sky at my true local astronomical midnight, it looked like God had turned out the lights.
I hope I can make sense out of this question. Suppose I have an image of the sky and know on that image say the RA/Dec and x,y position of 20 stars, and the time the image was taken. The zenith is somewhere in the middle. Now suppose one hour later I have another image of the sky, and would like...
Mysterious Night Sky Object - Help!?
Well, I've commented on others' questions on a number of occasions, but something just occurred which has thrown me for a loop, and I could really use an opinion or two. I've been into amateur astronomy for 43 years, and have seen any number of very...
Sky waves transmission is done using the total internal reflection phenomena. The waves reflect as we go to a rarer medium from a denser medium.
My book states that high frequency waves cannot be used for sky waves. IT says it will penetrate the atmosphere. I don't get it
refractive index...
Hello.
Last night i was stargazing with my skymaster 15x70 binoculars. everything went as usual - i observed star clusters, airplanes and sattelites passing by, etc.
while watching a little group of stars almost right above my head (85-90 degrees declination) a little "star" suddenly...
As the title. How many precent of the entire sky is investigated by the kepler telescope? I'm aware of that it's very little, but does anyone find a good page of this? I've looked, without results. I'm very thankful for help! :biggrin:
I was out walking my dogs at 3:00 a.m. (that i might let them off the leash to be dogs for awhile)
Over my head was a strange red cloud, circular and occupying about 2/3rds of the sky overhead, white faint whisps around its perimeter, as i got farther from the light pollution of town the...
Venus' synodic period is 583.92 days. Does that mean that Venus is 583.92/2 days the evening star and 583.92/2 days the morning star (with some period in between when it's probably to close to the sun to be visible)? What I want to know is some kind of formula so that I know where and when to...
This is even weirder than mammatus clouds.
http://news.yahoo.com/giant-tsunami-shape-clouds-roll-across-alabama-sky-192102289.html
http://news.yahoo.com/photos/giant-tsunami-shaped-clouds-1324327483-slideshow/
Homework Statement
Augustine continues to run around. He gets to the park and has the overwhelming urge to jump off a cliff and try to fly. He does so at an angle of 50 degrees to the horizontal while running at 14.5m/s. With his arms flapping, he rises in the air.
a) what is the highest...
Have you ever experienced the wonder of the night sky? If yes, then you know that the universe has so much to offer us. However, within the next decade or so, the beauty of the night sky will fade away with time itself. Why? Light Pollution is taking control of our night skies.
What is this...
Sunlight takes eight minutes to reach Earth. Meanwhile the sun and Earth have moved/rotated.
Suppose that the sun emitted two types of light, the 8-minute light and a spooky “zero-time light”. Where in the sky would we see/measure the second spooky sun - the real position of the sun?
The...
Color of Sky Without Atmosphere or 50 Times Denser
What would be the color of the sky if the Earth had no atmosphere?
Since the scattering of light is due to the fact that the wavelengths of blue are small enough to be obstructed by the particles in the atmosphere, whereas longer wavelengths...
Assuming, of course, that we simply rescaled our color perspectives so that longest wavelengths = red, shortest wavelengths = violet. Are there any such pictures?
My curiosity has been aroused by climate change debates, but my physics is inadequate. Perhaps I can get some help.
My question is simply: As viewed from the Earth surface, what percentage of the area of the visible sky is occupied by CO2 molecules? This could be expressed in simple terms...
Hey guys. I want to get started in looking at the night sky from my roof etc etc. I was thinking of getting Celestron SkyMaster Giant 15x70 Binoculars with a tripod as a starting tool which is only about $70-80. I don't want to buy a $4,000 telescope without knowing what I'm looking for lol...
Hi. I've searched this forum before for answers and it has never failed me before. I've seen threads on similar if not the same topic as this on here but they are either from years ago or the threads have been closed.
So here's the story, so tonight my brother in-law is at work and during...
When I look into space, I can't make it out, but I am looking at so much. It depresses me to that I may never know what's out there, that all of the questions I have may never be answered.
Does anyone else feel this way?
Homework Statement
I need to find how long it will take a supernova explosion to be a size of one arc sec here on earth, the distance to this explosion is 50 kilparsec
Homework Equations
The Attempt at a Solution
Any clue on what the formula is?
thanks
Hi, for all of you we´ve made new user-friendly interactive 3D model of solar system and night sky with real-time planet´s positions.
http://www.solarsystemscope.com/ (requires flash)
Application in a simple way helps students and laymen to understand the movements of the planets and...
hi i have noticed a pair of zig zagging lights about 6 months ago when i was having a smoke break, i decided to take a closer look and for the last 6 months I've been watching them everyday...they are there every night, i have even shown friends and family and they saw the same thing...it really...
I know the direction to the center of the galaxy is near Sagittarius. Therefore is it safe to conclude that the direction of our solar system's travel through the galaxy is 90 degrees from that point, along the strip of the Milky Way in the sky? As we are in the Orion arm, is the Orion...
How can one determine the color of another planet's sky from its atmosphere composition and parent star color? Earth's atmosphere is blue for most of the day, then turns red at sunset. Mars is sort of the opposite: it has a red sky which turns to a bluish hue at sunset.
Until someone tells me...
A star that has been ejected from a galaxy probably wouldn't be any different from stars within galaxies. It could be possible for a planet to orbit this star. What would the night sky appear like? Would the galaxies be too dim to see, and the night sky fully black?
Lets say that the star is...
When I point a camera at the sky and use the flash, it brightens up all the stars I'm looking at (not just the ones on the screen). Does anybody know why this is?
Dont ignore this as a hypothetical one, but really I have some doubt... suppose we made a very bright torch light and took it to Mars. Now assuming that the light is bright enough for me to observe it from Earth with the naked eye, would we see the light twinkling?
Is the twinkling only...
hi all
im studying polarization, and i want to check if i have the right idea about sky polarization.
basically i want to find the position of the sun when i know the angle theta (refer to the attachment) of the sun but doesn't know the exact position.
so i look at the portion of the sky...
Hi,
I was just wondering if some astronomers here could help me indentify 2 bright things in the sky. I'm not an astronomer, but I'm quite interested in the subject.
One of these things can be seen at about 6.00 P.M. to about 10.30 P.M. where I'm from (Southern Europe). It shows up in the...
I was wondering how someone would go about charting stars on their own, pencil and paper style. Particularly, I was curious how astronomers charted the positions of stars and paths of planets hundreds of years ago, and was hoping to replicate this. I understand it's probably very involved, but...
Sky is supposed to blue during the day because of maximum scattering of violet and blue light. But if they get scattered in the sky, how do they reach our eyes? With this logic i think the sky should be yellowish red during the day (which it surely isn't!)
With this notion i can understand why...
Given the following: Its a polar graph.
I am trying to figure out when is VENUS visable in the sky during this period (dawn, dusk, noon, midnight) ?
How do you figure that out? Also, Venus is red, Earth is green on the chart.
Thanks!
I was wondering if anyone here had experience using the image dataset of the Sloan Digital Sky Survey. Specifically, I want to find images of Mars from within their data. However, because they take one picture of the sky a night, and at a very small section of the sky, it's hard to predict...
Hello, PF community.
Past wednesday I was visiting the National Astronomical Observatory, which is located pretty close to my home, in Chile. It was about 10 pm, and I was waiting for my turn to see through the main telescope, while some astronomers were teaching us about the common stars in...
I guess I don't have much to say about this other than it's pretty amazing if it's true and I wanted to bring it to everyone's attention here.
http://www.sciencedaily.com/releases/2010/09/100909004112.htm
http://arxiv.org/abs/1008.3907