Time-lapse movie consisting of images acquired by the New Horizons spacecraft as it approached Pluto and Charon between May 28 and June 25, 2015. (Source: NASA/Johns Hopkins Applied Physics Laboratory/Southwest Research Institute) The New Horizons spacecraft has been sending home a steady stream of photos as it has closed in on Pluto. Now, the mission team has stitched a series of those images together to create the spectacular time-lapse animation above. Pluto is in the center, spinning on its axis. Charon, the planet's largest moon, is orbiting around it. As they loom ever larger in the frame, details on their surfaces become clearer. As described by NASA:
The images show Pluto and its largest moon, Charon, growing in apparent size as New Horizons closes in. As it rotates, Pluto displays a strongly contrasting surface dominated by a bright northern hemisphere, with a discontinuous band of darker material running along the equator. Charon has a dark polar region, and there are indications of brightness variations at lower latitudes.
The images in the time-lapse animation were acquired by the Long Range Reconnaissance Imager, or LORRI, camera, between May 28 and June 25 as the spacecraft raced closer and closer. In those 29 days, the spacecraft's distance to Pluto decreased from about 35 million miles to 14 million miles. Today, New Horizons is a bit more than 9 million miles away. It will make its closest approach — swooping just 7,750 miles above Pluto's surface — at 7:49:57 EDT on July 14. The mission team announced some news about Pluto yesterday: New Horizons has detected frozen methane on the planet's surface. This was not surprising, since the presence of the odorless, colorless gas on Pluto was first detected by Earth-based astronomers back in 1976. Scientists suspect that Pluto's methane came from the solar nebula out of which the solar system formed 4.5 billion years ago. Our own atmosphere also contains methane, at a concentration a bit below 1,850 parts per billion. Almost all of it came from biological processes, with very little coming from non-living sources. (Methane is one of the greenhouse gases that are increasing in the atmosphere thanks to our activities. That increase is helping to drive global warming and resulting changes to the climate.) By studying Pluto up close, scientists hope to learn more about the icy Kuiper Belt — the "third zone" of our solar system. We live in the inner zone, the realm of rocky planets: Earth, Venus, Mercury and Mars. The gas giants of the second zone are, of course, Jupiter, Saturn, Uranus and Neptune. It turns out that there are far more ice dwarf planets in the third zone, the Kuiper Belt, than all the other kinds combined. These bodies are believed to be embryos that never completed their development into full planets. New Horizons will be the first spacecraft to visit one of these mysterious worlds. And the hope is that it will provide new insights into how the solar system formed.