Perihelion is the closest point in a planet's orbit to the sun. Earth's perihelion occurs at 7:38 p.m. ET on January 2, 2024. The difference between perihelion and aphelion is about 3 million miles
Meteor showers occur when meteors originate from a single point in the sky. Meteors are caused by cosmic debris streams entering Earth's atmosphere. Most meteors are smaller than sand grains and never reach Earth's surface. Meteor storms produce at least 1,000 meteors per hour, most notably from Leonids
Discovered independently by Alan Hale and Thomas Bopp on July 23, 1995. Located 7.2 au from Sun, between Jupiter and Saturn. Nucleus measured 60±20 km in diameter, six times larger than Halley's Comet
Discovered independently by Lewis Swift and Horace Tuttle in 1862. Nucleus diameter is 26 km. Has 133-year orbital period in 1:11 resonance with Jupiter. Parent body of Perseid meteor shower
Comet tails become visible when illuminated by the Sun. Solar radiation causes volatile materials to vaporize and stream out. Coma forms around comet, tail points away from Sun
Halley's Comet appears every 72-80 years, visible to naked eye from Earth. First comet recognized as periodic, discovered by Edmond Halley in 1705. Orbit is highly elliptical with perihelion at 0.59 au, aphelion at 35 au. Retrograde orbit inclined 18° to ecliptic, with perihelion at 0.59 au