Halley's Comet

Definition

Halley's Comet is a periodic comet that is visible from Earth approximately every 75-76 years as it orbits the Sun. It is named after the English astronomer Edmond Halley, who calculated its orbit and predicted its return in 1758, making it the first comet whose return was predicted successfully.

5 Must Know Facts For Your Next Test

1. Halley's Comet is the most famous and well-studied periodic comet, with a period of approximately 75-76 years.
2. The comet's nucleus is composed of ice, rock, and dust, and as it approaches the Sun, the ice and dust form a glowing head and tail.
3. Halley's Comet was last visible from Earth in 1986 and is expected to return to the inner solar system in 2061.
4. The comet's orbit is retrograde, meaning it orbits the Sun in the opposite direction to the planets.
5. Observations of Halley's Comet have provided valuable insights into the composition and behavior of comets, which are remnants of the early solar system.

Review Questions

• Explain how Halley's Comet is related to the concept of orbits in the solar system.
  • Halley's Comet is a prime example of a periodic comet, which means it orbits the Sun and can be observed from Earth at regular, predictable intervals. The comet's orbit is elliptical, with an aphelion (farthest point from the Sun) and a perihelion (closest point to the Sun). Edmond Halley's calculations of the comet's orbit were a significant achievement, as they allowed him to predict the comet's return, demonstrating the predictable nature of orbits in the solar system.
• Describe how Halley's Comet relates to the overview of our planetary system.
  • Halley's Comet is a member of the solar system, orbiting the Sun along with the planets. Its periodic appearance and the insights it provides into the composition and behavior of comets contribute to our understanding of the broader planetary system. Comets like Halley's are remnants of the early solar system, and their study can reveal information about the formation and evolution of the planets and other celestial bodies.
• Analyze the role of Halley's Comet in the context of asteroids and planetary defense.
  • While Halley's Comet is not considered a threat to Earth, the study of comets and their orbits can provide valuable information for planetary defense against potential asteroid or comet impacts. Observations of Halley's Comet have helped scientists better understand the composition and behavior of comets, which can inform strategies for detecting and mitigating the risk posed by similar celestial objects that could potentially collide with Earth. Additionally, the long-term monitoring of Halley's Comet and other periodic comets contributes to our overall understanding of the dynamics of the solar system and the threats it may face.

Related terms

Periodic Comet: A comet that orbits the Sun and can be observed from Earth at regular, predictable intervals.

Orbit: The curved path an object takes as it revolves around another object in space, such as a planet orbiting the Sun or a comet orbiting the Sun.

Aphelion: The point in a comet's orbit when it is farthest from the Sun.