Topic: Space

NASA's Lucy spacecraft recently discovered a peanut-shaped asteroid named Donaldjohanson. The asteroid has an unusual shape and wobbles as it rotates.

Asteroids can have exciting histories, even if they're small. NASA's Lucy spacecraft found out that asteroid Donaldjohanson is a wobbling, peanut-shaped object that has been shaped by collisions, sunlight, and ancient water. The asteroid formed about 155 million years ago when fragments from a violent collision came together.

The asteroid's shape is unusual because it has two connected lobes joined by a narrow neck. Scientists think this type of structure formed when two fragments produced by an earlier collision merged under their own gravity. Lucy's close-up images and measurements revealed that the asteroid doesn't rotate in the simple way scientists expected. Instead, it turns end-over-end once every 10.5 days while also rocking back and forth around its long axis once every 26.5 days.

The encounter served as a practice run for Lucy's future visits to the Trojan asteroids. Scientists gained valuable insights into Donaldjohanson's evolution by comparing it with Bennu and Ryugu, two asteroids that have been examined up close through sample-return missions.

Why It Matters

This discovery matters because it helps us understand how asteroids form and evolve over time. It also shows the importance of studying small asteroids like Donaldjohanson, which can provide valuable insights into the early history of our solar system.

Key Facts

• Asteroid Donaldjohanson is a peanut-shaped object that wobbles as it rotates.
• The asteroid formed about 155 million years ago when fragments from a violent collision came together.
• Donaldjohanson has two connected lobes joined by a narrow neck, which likely formed when two fragments merged under their own gravity.
• The asteroid doesn't rotate in the simple way scientists expected; it turns end-over-end once every 10.5 days and rocks back and forth around its long axis once every 26.5 days.
• Lucy's close-up images and measurements revealed evidence of ancient water on Donaldjohanson's surface.

Key Terms

YORP effect

A subtle process driven by sunlight that can either slow or accelerate an asteroid's spin.

Implications

This discovery matters because it helps us understand how asteroids form and evolve over time. It also shows the importance of studying small asteroids like Donaldjohanson, which can provide valuable insights into the early history of our solar system.