Astronomical unit

High school (ages 12+)
Space & Astronomy

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/astronomical-unit

1. What is the formal definition?
2. What is the equivalence in light travel time?
3. Why did scientists change the astronomical unit in 2012?
4. How does the astronomical unit help us understand planets like Jupiter or Neptune?

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the formal definition?Exactly 149,597,870,700 meters, established in 2012
2. What is the equivalence in light travel time?Approximately 499.004783836 seconds
3. Why did scientists change the astronomical unit in 2012?They fixed it to a precise number so calculations for space missions and deep‑space observations become more accurate and consistent.
4. How does the astronomical unit help us understand planets like Jupiter or Neptune?We say Jupiter is about 5.2 AU away from the Sun and Neptune about 30 AU, which makes it easier to compare how far each planet is in a familiar scale.

Parallax: The apparent shift in an object's position when viewed from different locations, used to measure cosmic distances.
Perihelion and Aphelion: The points in an orbit where a celestial body is closest to and farthest from the Sun, respectively.
Exoplanet: A planet that orbits a star outside of our own solar system.