A Long Distance Look from LORRI images were published recently.

Pluto and Charon look like shrunken ovals here:

enter image description here

Why is this?

Is it due to Pluto and Charon's phases? Is the distance enough to observe not full phase?

I calculated that since the speed of Pluto is 4.6 km/s and the speed of New Horizons is 14.6 km/s, then the angle it observed is 17 degrees.

enter image description here

Is this correct and is this enough to observe not full phase?

  • 1
    $\begingroup$ Your diagram is wrong because speed is a scalar quantity, but you're using it as a vector (assuming it describes both magnitude and direction). Also, only the hypotenuse can be a straight line in this case. Here is New Horizon's current position and trajectory. The Sun-spacecraft-Pluto angles are nearly in a straight line. $\endgroup$
    – TildalWave
    Feb 5, 2015 at 19:56
  • $\begingroup$ Speed is a scalar quantity? When did God declared that? $\endgroup$
    – Dims
    Feb 5, 2015 at 20:00
  • 5
    $\begingroup$ On the very first day, according to Genesis 1:3 $\endgroup$
    – TildalWave
    Feb 5, 2015 at 20:04
  • 7
    $\begingroup$ @Dims velocity is a vector. Speed is a scalar. $\endgroup$ Feb 6, 2015 at 0:13
  • $\begingroup$ @TildalWave okay God was speaking English and was... American? Will know this. Now. Why do you think this is vector diagram? $\endgroup$
    – Dims
    Feb 6, 2015 at 4:41

1 Answer 1


Per New Horizons science team member John Spencer, via Emily Lakdawalla, the spacecraft is not yet close enough to fully resolve the the shapes of Pluto and Charon. Their apparent shape is dominated by the camera / telescope's point spread function, which is "slightly teardrop shaped, giving that gibbous appearance".

  • $\begingroup$ Can you also explain the latest photos? They all have a kind of smear effect artefacts $\endgroup$
    – rubo77
    May 14, 2015 at 4:03
  • $\begingroup$ @rubo77 If you're referring to these photos they're both heavily processed (which can cause various artifacts depending on the type of processing, which they have not detailed) and overexposed (which causes CCD blooming and streaking). $\endgroup$ May 14, 2015 at 4:33
  • $\begingroup$ Here the pictures have all those Streaks to the right $\endgroup$
    – rubo77
    May 14, 2015 at 7:11

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