Few hours ago NASA released a bunch of new images of Pluto received from New Horizons. Three of those images show a breathtaking backlit picture of Pluto and clearly put in evidence the dwarf planet’s atmosphere.
The image shown here was been obtained by manually stacking the three backlit pictures and enhancing the contrast, in an attempt to extract as much details as possible from the original images.
The three small dots in the bottom left area are most likely generated by a background star, which appears 3 times because of the alignment process has been centered on Pluto. The spacecraft took those 3 pictures at 2015-07-14 19:06:35 UTC with an interval of just 1 second between each frame. The fact that the 3 dots are not evenly spaced most likely means that the alignment process, which was manual and focused on Pluto’s disc, was not perfect.
What’s interesting is that a similar 3 dots pattern appears, barely visible, on the right hand side of the image, through the haze of Pluto’s atmosphere. A possible explanation is that New Horizons also captured an occultation of a background star. If this is the case, it is quite likely that the New Horizons team has planned this in advance in order to learn details about Pluto’s atmosphere (as they did with Charon).