1.9M views · 10K reactions | How well do you know our planets? 敖 All the planets in our solar system vary in size and distance from the sun, but just how different are they? | BBC Earth | Facebook

🌋 Could lava tubes hide signs of life on Mars? To find out, NASA researchers went deep beneath Hawai‘i’s volcanoes to study Earth’s own lava tubes – places where life survives in dark, extreme conditions. Join the expedition in our new documentary as astrobiologists test the technologies that will guide future NASA missions to detect and discover life beyond Earth. Don’t miss Our Alien Earth: Hawai’i, streaming now on NASA : https://go.nasa.gov/4sdN5vP | NASA Solar System Exploration