This video describes the comet C/2025 A6 (Lemmon), which will be visible to the naked eye in the Northern Hemisphere in October 2025. The first half of the video shows the orbit of this comet, while the second half displays its trajectory against the backdrop of the stars as seen from the Earth.
The comet was discovered in January 2025 at the Mount Lemmon Survey Observatory. Before entering the inner Solar System, its orbital period around the Sun was about 1350 years. However, the comet passage near Jupiter reduced this period by almost 200 years. In late 2024, the comet passed through the outskirts of the Greek camp of Jupiter Trojan asteroids. It spent the period from March to July 2025 in the main asteroid belt. In August, the comet appeared much brighter than predicted. In September, its ion tail became active, extending two angular diameters of the Moon. In addition to the gas tail, it may also have a second tail made of dust. The comet is moving in the opposite direction to the planets, so its speed will reach 80 km/s relative to the Earth. This will cause it to move quickly against the background of the constellations.
In October, it will be in the constellation Ursa Major and will pass under the well-known Big Dipper. On October 16, it will fly less than one degree from Cor Caroli, a bright star in the constellation Canes Venatici. On October 21, 2025, comet C/2025 A6 (Lemmon) will pass at a minimum distance of 89 million kilometers from the Earth. Crossing the constellation of Boötes, the comet can increase its brightness to 2nd magnitude, which is comparable to the stars of the Big Dipper. However, it will become increasingly difficult to observe the comet as the angular distance between it and the Sun decreases. During the second half of October, the comet will be bright enough to try to see it with the naked eye. To do this, it is advisable to stay away from bright city lights. On November 8, comet C/2025 A6 (Lemmon) will pass perihelion and will be at its closest distance from the Sun: 79 million kilometers. After that, it will begin its journey back to the aphelion of its orbit, which is approximately 220 AU from the Sun. Unfortunately, residents of the Southern Hemisphere will have extremely unfavorable conditions for observing the comet.
Modeling and rendering were performed by author of this video using own software. The calculations took into account the mutual influence of the Sun, all the planets of the Solar System, the Moon and the comet on each other. Relativistic effects were also taken into account in the calculation. Non-gravitational effects associated with the comet nucleus matter evaporation and the possible collision of fragments with each other were not taken into account. Throughout part of this video, the sizes of celestial bodies are shown to be greatly exaggerated compared to the distances between them.
The track Chasing Ghosts by Philipp Weigl sounds in this video. This track was not changed.
