The latest of New Horizon’s discoveries is the exact size of Pluto. We’ve known its mass pretty much ever since Charon was discovered (a satellite gives you the perfect information to calculate mass) but diameter is trickier, especially for an object that has an atmosphere. Well, now New Horizons is close enough to measure it accurately, and it’s a bit wider than scientists thought: about 1,473 miles (2,370 kilometers) across. This means its composition must tend more towards ice and less towards rock than they’d expected. Which is cool; you learn way more from the unexpected than the expected. 😉
And now, just under 10 hours to go for closest approach!