Triton is one of the moons of Neptune. It's also one of the most interesting moons in the solar system. Sadly, we've only flown by it once, when Voyager 2 passed the moon on this day 25 years ago.
To celebrate this anniversary, the Lunar and Planetary Institute (LPI) released a high-resolution map taken by Voyager of (what I estimate to be) about 65% of Triton's surface. Dr. Paul Schenk, a planetary scientist at the LPI wrote a blog post about this, and helped to remind us that Triton isn't just some hunk of ice. Rather, it is an amazing and exotic frozen world:
In the intervening quarter century and its many discoveries, I think we have tended to forget how strange and exotic Triton really is! Its effective surface age may be a little as 10 million years, clearly implying that active geology is going on today. The cantaloupe terrain, which I interpreted back in 1993 as due to crustal overturn (diapirism), hasn’t been seen anywhere else. The volcanic region, with its smooth plains and volcanic pits large and small, is the size of Texas. And the southern terrains still defy interpretation.
The video below is an animation created from the Voyager images, and shows what Voyager (probably) saw as it zipped past the moon. It is also the best-ever map of Voyager 2's data of Triton.
Quick facts about Triton:
- It is the largest moon in the solar system (with a radius of 2,700 km), and is even larger than Pluto.
- Triton has a retrograde orbit, meaning it orbits Neptune "backwards"
- Triton has a tangible atmosphere. The moon is so cold that the nitrogen in the atmosphere condenses and covers the surface with frost, which is why Triton seems so shiny.