Question

If Earth’s Moon were replaced with a typical neutron star, what would the angular diameter of the neutron star be as seen from Earth?

Answer 1

`0.00005202\ \text{rad}=0.003^(\circ)`

Step-by-step explanation:

d = Diameter of typical neutron star = 20 km = 20000 m

D = Distance between Earth and Moon =
`384.4* 10^6\ \text{m}`

Here,
`D>>d` so we use small angle approximation

`\delta=(d)/(D)\\\Rightarrow \delta=(20000)/(384.4* 10^6)\\\Rightarrow \delta=0.00005202\ \text{rad}=(0.00005202* 180)/(\pi)=0.003^(\circ)`

The angular diameter of the neutron star would be
`0.00005202\ \text{rad}=0.003^(\circ)` from Earth.