P7 - Last min revison notes the bare bones

what is a sidereal day - time time it takes for the earth to spin on its axis once this takes 23 hours and 56 mins which is 4 mins shorter than a solar day which is the time it takes for the sun to appear in the same place this takes 24 hours

they takes different times because within a day the earth also moves along its orbit  to to counter this the earth needs to spin a bit more to get the sun in the same place

we see different stars at different times of the year because we are on a different side of the earths orbitwhere there are different stars

the moon takes 24hours and 49 mins to be is the same place in the sky - for the reason that the moon has moved allong its orbit

the planets that are near to earth appear to move in  odd patterns across the sky and this is becuase at different times the planet will be infront of us in its orbit as it moves faster than us so it will go forward and if we then move faster than it it will appear to move forward

lunar elclipses  - formation  = sun - earth -moon

solar eclipses = sun- moon -earth

power of a lense= 1/ focal length in metres

anglar magnification = focal length of objectve lense/ focal length of the eyepiece

parallax is used to…