ESA’s Hera mission launched toward the asteroid moon Dimorphos on October 7, 2024. Its goal is to investigate the aftermath of humanity’s first planetary defense test in 2022, when DART struck the little asteroid. As Hera sailed off on its mission, it looked back at Earth and caught the above view of our home planet and the moon.
Hera took these images as a part of a test of its Thermal Infrared Imager (TIRI) instrument, which was a contribution from JAXA. So these thermal images give us a different view of the green-and-blue Earth we normally see. Hera took these images between October 10, when it was about 870,000 miles (1.4 million km) away, to October 15, when it was about 2.3 million miles (3.8 million km) away.
This image nicely illustrates the size of the moon compared to Earth, and how far away it orbits from us. It’s also a nice visualization to have when we talk about asteroids making “close” passes by Earth. Sometimes space rocks come even closer to us than the satellites in low-Earth orbit. In those cases, asteroids zip past us about 100 times closer than the moon. But many times the asteroids that pass “close” are 30 to 40 lunar distances away. Check out the table of known upcoming closest approaches here to see how many lunar distances (LD) away is common for asteroids passing near Earth.
The moon’s orbit isn’t quite circular. At its closest, it’s about 226,000 miles (363,300 km) away. When the moon is at its farthest from Earth, it’s about 252,000 miles (405,500 km) away. And did you know that when the moon and Earth are at their farthest apart, you could take all the other planets in the solar system – Mercury, Venus, Mars, Jupiter, Saturn, Uranus and Neptune – and line them up side-by-side within the space between Earth and the moon? Try to picture all the other planets wedged together between us and the moon in the image above.
The planets are quite small compared to the size of our solar system. Our solar system contains quite a lot of space.
Bottom line: The Hera mission is on its way to the asteroid Dimorphos. But first it looked back to catch a view of Earth and the moon from space.
Read more: Voyager 1: 1st portrait of Earth and moon 45 years ago today
The post Hera spots Earth and the moon from space. See it here! first appeared on EarthSky.
