Parsec definition | Stars, black holes and galaxies | Cosmology & Astronomy | Khan Academy

TL;DR

Parsec is a unit of distance equal to approximately 3.26 light years, derived from the parallax angle of one arc second.

Transcript

You've probably heard the word parsec before in science fiction movies or maybe even some things dealing with astronomy. And what I want to do in this video is really just tell you where the word and the definition of the word really come from. And just to kind of cut to the chase, it's just a unit of distance. It's just about 3.26 light years. But... Read More

Key Insights

• 🙂 A parsec is a unit of distance in astronomy equal to approximately 3.26 light years.
• 🫠 Its name is derived from the words "parallax" and "arc seconds," representing the distance with a parallax angle of one arc second.
• 🔺 The distance of an object in parsecs can be calculated using trigonometry and the tangent of the parallax angle.
• 🫠 Objects located at one parsec from Earth have a parallax angle of one arc second.
• 🆘 The concept of parsec helps astronomers measure distances in the universe.
• 🧘 Parsecs are used to study the positions and movements of celestial objects.
• 🍉 The term "parsec" is commonly used in science fiction movies and literature.

Questions & Answers

Q: What is a parsec?

A parsec is a unit of distance equivalent to about 3.26 light years, derived from the parallax angle of one arc second.

Q: Where does the term "parsec" come from?

The term "parsec" is derived from the words "parallax" and "arc seconds," representing the distance an object must be from Earth to have a parallax angle of one arc second.

Q: How is the distance of a parsec calculated?

The distance of a parsec can be calculated using trigonometry and the tangent of the angle formed by the parallax of one arc second.

Q: What is the significance of a parallax angle of one arc second?

A parallax angle of one arc second indicates that an object is located at a specific distance from Earth, which is defined as one parsec.

Summary & Key Takeaways

• Parsec is a unit of distance that is approximately 3.26 light years.

• The term "parsec" is derived from the "par" in parallax and the "second" in arc seconds.

• It represents the distance an object needs to be from Earth to have a parallax angle of one arc second.