The term "Apollo Asteroid" is commonly used in astronomy to refer to a type of asteroid that has an orbit that crosses Earth's orbit. The word "Apollo" is spelled with three syllables: /əˈpɑː.loʊ/. The first syllable is pronounced with a schwa sound, while the second syllable has a long "ah" vowel sound. The final syllable starts with a "l" sound and ends with a long "o" sound. The word "Asteroid" is spelled with four syllables: /ˈæs.tə.rɔɪd/. It comprises three consonants, three vowels, and two diphthongs.
Apollo asteroids are a class of Near-Earth Objects (NEOs) that cross the orbit of our planet. They are named after the first asteroid of this class, 1862 Apollo, which was discovered on April 24, 1932. Apollo asteroids are characterized by their highly elliptical orbits that bring them within the Earth's vicinity. These celestial bodies follow a path around the Sun that intersects with Earth's orbit, but they do not pose an immediate threat of collision.
The term "Apollo" has become synonymous with asteroid groups that have Earth-crossing orbits and a minimum orbit intersection distance (MOID) of less than 0.05 astronomical units (AU) or about 7.5 million kilometers. Apollo asteroids are classified as a subset of the larger group of Near-Earth Asteroids (NEAs).
These NEOs are of great interest to scientists and astronomers due to their proximity to Earth. Studying Apollo asteroids can provide crucial insights into the formation and evolution of our solar system. Researchers use various observational techniques, including radar and spectroscopy, to gather data about these asteroids and gain a better understanding of their composition, structure, and potential impact hazard.
To date, thousands of Apollo asteroids have been discovered, with sizes ranging from a few meters to several kilometers in diameter. Despite their close encounters with Earth, the vast majority of Apollo asteroids do not pose a direct threat. Nevertheless, continuous monitoring and research on these celestial bodies are essential in our efforts to better comprehend the dynamics of our solar system and assess any potential risks.
The word "Apollo" in "Apollo Asteroid" is derived from the Greek god Apollo, who was known as the god of light, knowledge, and prophecy in ancient Greek mythology. In astronomy, "Apollo" is used to refer to a particular group of Near-Earth Objects (NEOs) that have Earth-crossing orbits.
The term "Apollo Asteroid" was first coined in the early 1980s by German astronomer Karl Reinmuth. He named this group of asteroids after the Greek god Apollo due to their frequent close encounters with Earth. These asteroids are characterized by their highly elliptical orbits that sometimes bring them within Earth's vicinity.
The name "Apollo" alludes to the mythological story of Apollo shooting arrows from his golden bow, which symbolizes these asteroids potentially colliding with Earth. It reflects the inherent danger they pose if their orbits were to intersect with our planet.