From the May 2018 issue

How large does the Sun appear from Mercury and Venus, as compared to how we see it from Earth?

Robert Harrison Los Ranchos, New Mexico
By | Published: May 31, 2018 | Last updated on May 18, 2023
The apparent size of the Sun (with a physical diameter of about 865,000 miles [1.4 million kilometers]) varies with its distance from the observer. On Earth, where we average a distance of 93 million miles (150 million km) from our star, the angular diameter of the Sun is about half a degree (0.5°).

Mercury orbits the Sun at an average distance of about 36 million miles (58 million km). As a result, the angular diameter of the Sun from Mercury is much larger: about 1.4°. Venus’ average distance from the Sun is about 67 million miles (108 million km), and the Sun’s angular diameter from this planet is about 0.7°.

It is worth noting that the planets’ orbits are not quite circular. Between perihelion and aphelion, the angular diameter of the Sun as seen from Earth changes by about 3 percent. On Mercury, that change is nearly 53 percent, while on Venus, it’s a little over 1 percent.

Alison Klesman 
Associate Editor