What are the “Morning Star” and the “Evening Star”?
Mercury and Venus, due to their inferior orbits, always appear close to the Sun and are difficult to see except in the Twilight hours. Mercury and Venus are sometimes referred to as “Morning Star” and “Evening Star”. However, they are really not stars but planets.
Why did the ancients mistake the planets Mercury and Venus for stars?
Mercury and Venus appear bright during twilight hours when the stars are usually faint. Mercury is sometimes as bright as the bright-stars Sirius. Venus appears brighter than Mercury <sometimes even ten times brighter>.
What is a satellite transit?
When a satellite of a planet comes between the Earth and the planet, the event is called a satellite transit. For example, if a satellite of Jupiter is in transit, it can be seen with a telescope as a dark dot on the brighter disc of the planet.
Why does the Moon brighten and darken in phases from full Moon to new Moon and vice versa?
In the case of the Earth and the Moon, the side facing the Sun is brightly lit, while the opposite side remains dark as it is facing away. The phases of the Moon occur due to the relative positions of the Moon as viewed from Earth.
Do the planets exhibit phases (like the Moon) when viewed from Earth?
Yes. The inferior planets do.