Why is there day and night? - NASA
Why is there day and night? Answer: Clearly, when you see the Sun shining in the sky, it is day, and when you don't it is night. So the real question is "why is the Sun in the sky at some times and not at others?" We can see that the Sun seems to move across the sky starting in the east in the morning, moving toward the south at noon, and then ...
Why is space black? - NASA
At night, when that part of Earth is facing away from the Sun, space looks black because there is no nearby bright source of light, like the Sun, to be scattered. If you were on the Moon, which has no atmosphere, the sky would be black both night and day. You can see this in photographs taken during the Apollo Moon landings.
Teachers' Center Activity: Sun Motion - NASA
Give each student a stick-on dot to be put on the drawing in the place they think the Sun will be in one hour. In an hour's time, take the easel and students to the same location outside. Be sure the easel is in the exact location as it was earlier. With the help of the students, locate on the previously drawn picture the Sun's current position ...
What are the phases of the Moon? - NASA
The gibbous moon appears to grow fatter each night until we see the full sunlit face of the Moon. We call this phase the full moon. It rises almost exactly as the Sun sets and sets just as the Sun rises the next day. The Moon has now completed one half of the lunar month. During the second half of the lunar month, the Moon grows thinner each night.
What causes a "falling star"? - NASA
A "falling star" or a "shooting star" has nothing at all to do with a star! These amazing streaks of light you can sometimes see in the night sky are caused by tiny bits of dust and rock called meteoroids falling into the Earth's atmosphere and burning up. The short-lived trail of light the burning meteoroid produces is called a meteor.
StarChild: The planet Mercury - NASA
Mercury is the smallest planet in our solar system. Mercury is about the same size as our Moon. It is very close to the Sun. Mercury travels around the Sun faster than any other planet. That is how it got its name. It was named after Mercury, the swift messenger of the gods in ancient Roman mythology. Mercury can only be seen from Earth just ...
Why do stars twinkle? - NASA
This means that some of the light reaches us directly and some gets bent slightly away. To our eyes, this makes the star seem to twinkle. You will notice that stars closer to the horizon will appear to twinkle more than other stars. This is because there is a lot more atmosphere between you and a star near the horizon than between you and a ...
StarChild: Cosmology - NASA
Aristotle, who lived from 384 to 322 BC, believed the Earth was round. He thought Earth was the center of the universe and that the Sun, Moon, planets, and all the fixed stars revolved around it. Aristotle's ideas were widely accepted by the Greeks of his time. The exception, a century later, was Aristarchus, one of the earliest believers in a ...
The Phases of the Moon - NASA
The Phases of the Moon. visible. Return to the StarChild Main Page. Go to Imagine the Universe! (A site for ages 14 and up.) High Energy Astrophysics Science Archive Research Center (HEASARC) Astrophysics Science Division (ASD) NASA/ GSFC. The StarChild Team. Acknowledgments. Dr. Laura A. Whitlock.
StarChild: The planet Mercury - NASA
On the side facing away from the Sun, or the night side, the temperature drops to -183 degrees Celsius. Scientists have detected a magnetic field surrounding Mercury, though it is not as strong as the field around the Earth. Scientists theorize that Mercury's field is due to an iron-bearing core or possibly to the solar winds. Mercury's ...