# Thread: Need help please

1. ## Need help please

This question has been giving me grief all morning, could anyone help me out:

If the moon's diameter is 3,476 km and its average distance from Earth is 384,000 km, use the small angle formula to calculate the Moon's size in the sky.

angular size / 206,265" = diameter/ distance

Report your answer to the nearest arc-second (")

2. oh yeah and then:

Convert your answer to the previous question to find the Moon's size in arc-minutes (')

Give your answer to the nearest arc-minute (no decimal places)

Your answer should be close to the equivalent of 1/2 degree.

3. Originally Posted by forza85
This question has been giving me grief all morning, could anyone help me out:

If the moon's diameter is 3,476 km and its average distance from Earth is 384,000 km, use the small angle formula to calculate the Moon's size in the sky.

angular size / 206,265" = diameter/ distance

Report your answer to the nearest arc-second (")
angular size=206265*dia/dist=206265*3476/384000~=1867 seconds of arc

RonL

4. Originally Posted by forza85
oh yeah and then:

Convert your answer to the previous question to find the Moon's size in arc-minutes (')

Give your answer to the nearest arc-minute (no decimal places)

Your answer should be close to the equivalent of 1/2 degree.

1867 secods of arc= 1867/60 minutes of arc ~=31 minutes of arc

31 minutes of arc=31/60 degrees ~= 1/2 degree.

RonL