By Mike Hubbartt, © Copyright 2011-2017, All Rights Reserved.

Pluto Facts:

  • Location: Mostly beyond the orbit of Neptune
  • Size: smaller than the 8 planets, smaller than Eris, and smaller than our moon
  • Orbit: 29 – 49 AU (average 39 AU)
  • Orbital Period: 247.92 Julian years *
  • Average Distance from Earth: 40.7 AUs *
  • Diameter: 2,274 km
  • Discovered: 1930 by Clyde W. Tombaugh
  • Atmosphere: Little is known, but probably nitrogen, CO, methane
  • Interesting facts: it was reclassified as a dwarf planet in 2006
  • Total number of moons: 4 (Charon, Nix, Hydra, and P4)
  • Click here for Wolfram|Alpha data on Pluto

* = Courtesy of Wolfram Astronomy Assistant

I’ve already covered the four gas giants, so now it is time to turn our attention and Starry Night Pro Plus software to Pluto. Pluto enjoyed planetary status from 1930 (when discovered by Tombaugh) until 2006, when it was reclassified as a dwarf planet. There are several known dwarf planets, some in the kuiper belt region and one (Ceres) in the asteroid belt that was previously considered to be an asteroid.

Pluto is so far away that even the Hubble telescope has difficulties getting good quality images. Fortunately the New Horizons mission (click here to read about the location of the probe on 1/18/2011) took loads of great pictures when it passed Pluto in 2015. Launched in 2006, this mission is still exciting as it is on the way to some planets in the Oort Cloud.  While there have been discussions about reclassifying Pluto as a planet, our first visit to a dwarf planet was a major accomplishment for NASA.

Update: July 11, 2017

The first picture I downloaded from the 7-15-2015 approach to Pluto.  It is an amazing image, and the New Horizons probe gathers a lot of data that took over a year to send back to Earth, as there was so much and in such great detail.  We’ve never had images like this of Pluto, and I hope this inspires NASA to schedule another probe with higher definition cameras for the outer planets and dwarf planet Pluto.


Update: July 20, 2011

A new moon of Pluto was announced by NASA on Twitter today. P4 was discovered using the Hubble Telescope and the picture of it, as well as Pluto and the other 3 moons is shown below:

Update: June 24, 2011

Click here for some excellent information plus a nice picture of the June 23, 2011 SOFIA Pluto Occulation. End of update

This is a screen shot of Pluto and Charon taken with Starry Night Pro Plus 6.4.2 on 1/19/2011:

Since I showed how planets look from nearby moons for the gas giants, I might as well do the same for Pluto.First of all, this image of Charon was taken in Starry Night Pro Plus:

Here is Pluto as seen from Charon:

Here is Charon as seen from Pluto:

The status of Pluto does not detract from the impressive accomplishments of our scientists to send a probe so far away to gather and return data about this mostly unknown part of our solar system. Who knows when we will send another probe out to the Kuiper belt region of the solar system? Space vessel propulsion systems are being examined  – new technologies may result in another mission sooner rather than later. But then, we do need another mission to the asteroid belt, so the future of space exploration looks bright indeed.



7-11-2017 – Added new image of Pluto, plus updated content to show New Horizons has passed Pluto and is proceeding on to the Oort Cloud for the next phase of its mission.

6-24-2011 – Added Orbital Period Data, Average Distance to Earth, plus reference to June 23, 2011 SOFIA Occulation.

2-14-2011 – Added names of all moons.

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