Comets are icy bodies that orbit the Sun, often following highly elongated paths. As they approach the Sun, heat causes their ices to vaporize, forming bright comas and distinctive tails that can stretch millions of kilometers. These ancient travelers carry clues about the formation of the solar system and have captivated both astronomers and the public for centuries.
1. Halley’s Comet
Orbital Period: ~76 years | Last Perihelion: 1986 | Next Perihelion: 2061
Perhaps the most famous comet of all, Halley’s Comet has been recorded since ancient times, with sightings documented as far back as 240 BC. It was identified as a periodic comet by Edmond Halley in 1705. Every return of this bright comet offers scientists the opportunity to study its structure and behavior. During its 1986 approach, spacecraft such as Giotto provided close-up images, revealing a dark, peanut-shaped nucleus.
2. Comet Hale-Bopp
Orbital Period: ~2,533 years | Perihelion: 1997
Discovered in 1995, Comet Hale-Bopp was one of the most brilliant comets of the 20th century. It was visible to the naked eye for an astounding 18 months, captivating millions across the globe. Hale-Bopp’s long-lasting visibility and dual dust and ion tails made it a subject of significant scientific study, providing new insights into cometary composition and structure.
3. Comet Shoemaker-Levy 9
Discovered: 1993 | Impact with Jupiter: 1994
Shoemaker-Levy 9 made history by being the first comet observed to collide with a planet. In 1994, fragments of the comet slammed into Jupiter, creating massive explosions in the planet’s atmosphere. The impacts left dark scars that were visible for months, offering scientists a unique opportunity to study planetary impacts and their effects on planetary atmospheres.
4. Comet 67P/Churyumov–Gerasimenko
Orbital Period: ~6.45 years | Notable Mission: ESA’s Rosetta (2014)
This small comet gained international attention through the European Space Agency’s Rosetta mission, which sent a spacecraft to orbit the comet and deploy the Philae lander on its surface. The mission revealed the comet’s surprisingly complex surface, with cliffs, pits, and dust jets. It also detected organic molecules, providing clues about the role comets may have played in seeding life on Earth.
5. Comet NEOWISE (C/2020 F3)
Perihelion: 2020 | Orbital Period: ~6,800 years
Comet NEOWISE became a stunning sight in the night sky during the summer of 2020. It was one of the brightest comets visible in recent years and displayed a long, glowing tail. Its appearance allowed astronomers to gather valuable data on comet behavior close to the Sun, while amateur astronomers worldwide enjoyed its rare brilliance.
6. Comet Hyakutake
Perihelion: 1996 | Orbital Period: ~72,000 years
Discovered just a few months before its closest approach, Comet Hyakutake provided a spectacular display in 1996. It passed extremely close to Earth—just 15 million kilometers away—giving astronomers a chance to observe its tail stretching over 100 degrees across the sky. The encounter also allowed scientists to detect unexpected emissions, such as X-rays, from the comet.
7. Comet Tempel 1
Orbital Period: ~5.5 years | Notable Mission: NASA’s Deep Impact (2005)
Comet Tempel 1 was the target of NASA’s Deep Impact mission, which intentionally crashed a spacecraft into the comet’s surface to study its interior composition. The collision revealed water ice and organic material, confirming that comets are a rich source of essential ingredients for life. Tempel 1 became the first comet to be closely observed before and after an impact event.
Comets are more than just fleeting celestial visitors—they are time capsules from the early solar system, preserving pristine material from billions of years ago. As new comets are discovered and explored by future missions, these icy wanderers will remain a source of fascination and scientific inquiry.