Halley's Comet

Definition

Halley's Comet is a periodic comet that is visible from Earth 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 regular return to the inner solar system.

5 Must Know Facts For Your Next Test

1. Halley's Comet was first observed and recorded by Chinese astronomers as early as 240 BCE, making it one of the oldest known periodic comets.
2. Edmond Halley's calculations in the 18th century correctly predicted the comet's return in 1758, confirming that it was a periodic comet.
3. Halley's Comet has an orbital period of approximately 75-76 years, meaning it is visible from Earth every three-quarters of a century.
4. The comet's closest approach to the Sun, known as perihelion, occurs at a distance of about 88 million kilometers, or 0.59 astronomical units.
5. Halley's Comet is composed of ice, dust, and rocky material, and its bright, glowing tail is formed by the interaction of solar radiation and the comet's nucleus.

Review Questions

• Explain how Edmond Halley's observations and calculations contributed to our understanding of Halley's Comet.
  • Edmond Halley, an English astronomer, played a crucial role in our understanding of Halley's Comet. By carefully observing the comet's appearance and movement, Halley was able to calculate its orbit and predict its regular return to the inner solar system every 75-76 years. This confirmation that Halley's Comet was a periodic comet, rather than a one-time celestial event, was a significant scientific breakthrough that laid the foundation for our modern understanding of comets and their behavior.
• Describe the relationship between Halley's Comet and Kepler's Laws of Planetary Motion.
  • Halley's Comet, as a periodic comet, follows an elliptical orbit around the Sun, which is in accordance with Kepler's First Law of Planetary Motion. The comet's orbital period of approximately 75-76 years also aligns with Kepler's Third Law, which states that the square of a planet's (or comet's) orbital period is proportional to the cube of its semi-major axis. The predictable and regular appearance of Halley's Comet, as it completes its elliptical orbit, demonstrates the applicability of Kepler's Laws to the motion of comets and other celestial bodies in the solar system.
• Analyze the significance of Halley's Comet in the context of our understanding of the solar system and the broader universe.
  • Halley's Comet holds a unique place in the history of astronomy and our understanding of the solar system. As one of the oldest known periodic comets, its regular appearance has provided valuable insights into the dynamics and evolution of the solar system. The comet's predictable orbit, as described by Kepler's Laws, has allowed astronomers to study its composition, structure, and interactions with the Sun and other celestial bodies, furthering our knowledge of comets and their role in the formation and evolution of the solar system. Additionally, the study of Halley's Comet has contributed to our understanding of the broader universe, as it serves as a model for the behavior and characteristics of other periodic comets and their potential impact on the planets and the overall structure of the cosmos.

Related terms

Periodic Comet: A comet that follows a predictable orbit around the Sun, returning to the inner solar system at regular intervals.

Orbital Period: The time it takes for a celestial body, such as a comet, to complete one full revolution around the Sun.

Aphelion: The point in a comet's orbit when it is farthest from the Sun, marking the apogee of its elliptical path.