How Do You Calculate the Radius of the Sun Using Its Angular Size?

[needhelp83]

The Sun subtends an angle of about 0.5 degrees to us on the Earth, 150 million km away. What is the radius of the Sun?

theta=l/R

(2pi rad/360 degrees)0.5 degrees=2pi(150,000,000 km)

This should be simple, but the answer I get seems to not sound right at all

Have i set this up correctly?

 

[OlderDan]

The Sun subtends an angle of about 0.5 degrees to us on the Earth, 150 million km away. What is the radius of the Sun?

theta=l/R

(2pi rad/360 degrees)0.5 degrees=2pi(150,000,000 km)

This should be simple, but the answer I get seems to not sound right at all

Have i set this up correctly?

Why is the title of this thread rotational motion? This is something else. Your equation is correct for finding the diameter of the sun, and you do need to convert to radians as you have done. If I may change the letter for diameter to D, you have

theta = D/R

where R is the distance from the sun to the earth. Solve this for D and try your calculation again. Then remember to find the radius of the sun from D.

 

[needhelp83]

theta =D/R

(2pi rad/360°)(0.5°)=D/(150,000,000 km)

D=(1,308,997 km)

R=(1,308,997 km)/2= 654,499 km

Better?

 

[OlderDan]

theta =D/R

(2pi rad/360°)(0.5°)=D/(150,000,000 km)

D=(1,308,997 km)

R=(1,308,997 km)/2= 654,499 km

Better?

Much better