Naked eye astronomy Flashcards
What direction does the sun appear to travel across the sky and how often does it do this?
It appears to travel east to west, it does so every 24hrs
How long does it take the moon to return to the same spot in the sky?
24hrs and 50mins
How long is a sidereal day and why?
A sidereal day is 4 mins shorter than a solar day, it is because in the time it takes the earth to fully rotate once, it has also moved 1 degree in its orbit of the sun and so in the last 4 mins the sun has already appeared to have moved past its same point
Why do planets appear to go back on themselves in retrograde motion against the distant stars?
Because as the Earth orbits the Sun, so do other planets but at different speeds and so they appear in front as we approach them but as we overtake them they appear to go back on themselves and then once we have finished overtaking them they appear to loop back onto their original direction.
How do we see what we do at a new moon?
The new moon is when the moon is in between us and the sun and so all of the light falls on the part of the moon that we can’t see,
How do we see what we do at a half moon?
At a half moon the moon is at a right angle to the earth and sun meaning only half the side of the moon we can see is lit up,
How do we see what we do at a full moon?
A full moon occurs when the moon is furthest away from the sun and the earth is in between and so all of the side we can see is covered in light.
Why do we only ever see the same side of the moon?
The moon rotates on its axis at the same rate that it orbits the earth and so as it spins it so that a new part of the moon is facing the earth, it has moved to a position where the same side of the moon is again facing Earth
What is a solar eclipse?
A solar eclipse occurs when the moon is directly between the Earth and the Sun and so the moon’s shadow falls on the Earth, only a small section of the Earth in the shadows umbra will see a total eclipse whereas in the penumbra you will see a partial eclipse.
What is a lunar eclipse?
A lunar eclipse is when the moon’s orbit causes it to pass into the Earths shadow, a lunar eclipse covers the whole moon and can be seen anywhere the moon could be seen from.
Why do some stars appear not to move?
These stars appear not to move as they are so distant the appear fixed
How do we map the night sky and what are the two axis for this?
We map the night sky as the celestial sphere, the axis being right ascension, measured in minutes and seconds from the right hand side, and declination, measured in degrees up to 90 from the bottom.
