On January 10, 2025, Venus will reach its Greatest Eastern Elongation. Venus, the brightest "star" in the evening western skies, outshines everything else. Just after sunset, in the evening twilight, it is easy to spot this diamond in the sky.
Greatest Elongation refers to the largest angle formed between Earth, the Sun, and a planet—in this case, Venus. On this day, Venus will appear 47 degrees away from the Sun as seen from Earth. As both Earth and Venus orbit the Sun, the angle between Venus and the Sun (as viewed from Earth) changes. When the planets align with Venus between Earth and the Sun, the angle is zero, an event known as Inferior Conjunction. Since Venus orbits closer to the Sun and moves faster than Earth, this angle increases, eventually reaching a maximum of 47 degrees. After this point, the angle begins to decrease until it reaches zero again. When Venus aligns on the far side of the Sun relative to Earth, this is called a Superior Conjunction.
At Greatest Eastern Elongation, Venus will display a nearly half-phase and will set late in the evening. As the days pass, the angle between the Sun and Venus will gradually reduce, but Venus's apparent size will increase. The phase will change from half to a crescent as the distance between Venus and Earth decreases.
At Greatest Elongation, Venus's angular size will be 24.6 arcseconds, with the planet located 101,742,566 km from Earth. As Venus continues to approach Earth, its angular size will increase to 46 arcseconds by the end of February, while its distance decreases to 53,967,713 km. Venus will be closest to Earth on March 22, 2025, at a distance of 41,977,162 km, just before reaching Inferior Conjunction on March 23, 2025.
