Picture This

A day on Pluto, a day on Charon

Pluto’s day is 6.4 Earth days long. The dwarf planet’s largest moon, Charon, also rotates once every 6.4 days as the two worlds are tidally locked to each another. This sequence of images from the Long Range Reconnaissance Imager (LORRI) and the Ralph/Multispectral Visible Imaging Camera on NASA’s New Horizons spacecraft shows us full rotations of the two bodies.

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A supermassive black hole in action

Scientists often use the combined power of multiple telescopes to reveal the secrets of the universe — and this image of elliptical galaxy Hercules A is a prime example of when this technique is strikingly effective. Radio observations with the Karl G. Jansky Very Large Array were combined with the Hubble visible-light data obtained with the Wide Field Camera 3 to create this striking composite image.


Dark matter dominates in nearby dwarf galaxy

Dark matter is called “dark” for a good reason. Although they outnumber particles of regular matter by more than a factor of 10, particles of dark matter are elusive. Now, by measuring the mass of a nearby dwarf galaxy called Triangulum II, astronomers believe they may have found the highest concentration of dark matter in any known galaxy.

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A brighter Saturnian moon

Although Saturn’s moons Dione (near) and Enceladus (far) are composed of nearly the same materials, Enceladus has a considerably higher reflectivity than Dione. As a result, it appears brighter against the dark night sky. This image was taken by NASA’s Cassini spacecraft in visible light with the narrow-angle camera on 8 September 2015.

Book Reviews

Galactic Encounters

“With many great photographs — from Edwin Hubble to the Hubble Space Telescope — a robust approach to the science which is (usually) very well explained, and detailed footnotes, this is a history of galactic astronomy that should definitely find space on your bookshelf,” says reviewer Andy Sawers.