Further physics - studying the universe Flashcards Preview

Physics 21st Century > Further physics - studying the universe > Flashcards

Flashcards in Further physics - studying the universe Deck (274)
Loading flashcards...

How does the sun appear to move across the sky?

From east to west (I remember it by alphabetical order)


What is the time between the sun appearing at its highest point one day and the next called?

The solar day


How long is the solar day?



How long does it take for the moon to appear in the same place in the night sky from one day to the next?

24 hours + about 50 minutes, which is the time that the earth takes to rotate further to catch up with the moon as it orbits us.


How long does it take the stars to appear in the same place?

Slightly less than 24 hours.


What is a sidereal day?

The time taken for the earth to rotate 360 degrees


How long is the sidereal day?

23 hours 56 minutes


Why is the sidereal day shorter than the solar day?

We are orbiting the sun, so we need an extra 4 minutes to allow for the movement of the earth through space to put the sun where it was the previous day.


What does the moon orbit?

The earth


What causes the moon to be visible from earth?

It reflects some of the light from the sun.


How much of the moon is lit by the sun at any time?



Why does the moon appear to change shape from earth?

It is due to the change in the amount of the lit side of the moon that we can see.


What is the changing shape of the moon called?

The phases of the moon.


When the moon is almost directly between the earth and the sun, what shape moon do we see?

The crescent of the new moon


When the earth is almost directly between the sun and the moon what shape moon do we see?

The round full moon.


What is the time between one full moon and the next?

29.5 days.


What is the time between one full moon and the next called?

A lunar month.


What happens when the sun, moon and earth are directly in line?

It creates an eclipse


How does a solar eclipse happen?

The moon comes between the sun and earth, and the moons shadow falls on earth.


How can the tiny moon blot out the whole sun?

It is much closer to the earth, and they apparent size of the two objects from earth is almost the same.


Why can a solar eclipse only be seen from part of the earth?

The moon is a lot smaller than the earth, so the moons shadow covers a relatively small area.


How can a lunar eclipse happen?

When the moon passes into the earth's shadow.


From where on earth is a lunar eclipse visible?

From any part where the moon is visible at that time.


Why don't eclipses happen every time the moon orbits the earth?

The moon does not orbit the earth at the same angle as the orbit of the earth around the sun, the earth moon system is tilted slightly.


Which planets can be seen from earth with the naked eye?

Mercury, Venus, Mars. Jupiter and Saturn can also be seen, despite the distance, as they are very large objects.


What does the word planet actually mean?

It comes from the Greek for "wandering star", as the planets move across the other stars.


As the planets orbit the sun, and we keep orbiting too, what happens to the distance between us and the planets?

It changes.


What happens to the apparent brightness of the planets as the distance between us changes?

It changes.


What happens to the stars as the earth rotates?

They, and the planets, appear to move east-west.


What happens to the position of the planets against the background of the stars?

It changes due to their orbits around the sun.