The Moon forms another 90° or square angle with the Sun, but this phase is different from the First Quarter. This phase occurs when the Moon is positioned perpendicularly to the Earth-Sun axis.

See what moon phase it is tonight and find out when you can see the rest of the moon phases for 2025.

The cosine of its maximum phase angle needs to be 2(0.995)–1=0.99, so θ=8.1°. And the planet’s orbital radius then would have to be 1/sin(8.1°)=7.097 AU, which would place it between ...