New Horizons has reached Pluto

Pluto and its moon Charon are now more than fuzzy dots of light on a photographic plate. We are finally getting images of our farthest planet from close up. By “close up”, NASA means 7,800 miles. New Horizons, which was launched more than 9 years ago, is sending images of the little planet that was recently reduced to dwarf status. Interestingly, it’s a little bit larger than we thought. Earlier measurements by telescope were limited by the vast distance and by Pluto’s thin atmosphere. The planet looks dark, with a heart-shaped area of lighter material.

You can get news of the mission, as well as videos and still images, at

If all goes according to plan during the flyby Tuesday, New Horizons will map the surfaces of Pluto and Charon in detail, study the two objects’ geology, characterize Pluto’s wispy atmosphere and perform a number of other investigations.




Of course, Richard Hoagland has his own take on the discoveries.

Frankly, I prefer wild speculation to the pedestrian reports from scientists and officials.

Beginning in the 1960s, the Mariner and Viking missions explored nearby rocky planet,s while the Pioneer and Voyager missions showed us the outer gas giant planets. The two planets that are most difficult to explore are the nearest to the Sun, Mercury, and the farthest known, Pluto. NASA’s Messenger gave us images of Mercury before crashing into the planet. This mission was made difficult because Mercury is so close to the Sun.

Pluto was difficult to reach, not really because it is so far away, but because it is at a steep angle to the plane of the ecliptic. While most of the planets in our solar system are within  a narrow disk-shaped space around the Sun, Pluto moves above and below that plane. Its orbit is eccentric, which means that sometimes it is closer to the Sun than Neptune, while at other parts of it s orbit, Pluto is farther from the Sun. You can get information about Pluto’s orbit from Smithsonian.

It takes 248 Earth years for Pluto to complete one orbit around the Sun. Its orbital path doesn’t lie in the same plane as the eight planets, but is inclined at an angle of 17°. Its orbit is also more oval-shaped, or elliptical, than those of the planets. That means that sometimes Pluto is a lot nearer to the Sun than at other times, At times Pluto’s orbit brings it closer to the Sun than Neptune. The last time this happened was from 1979 to 1999. It won’t happen again until 2227.