Seventy days worth of solar system observations
from NASA's Kepler spacecraft, taken during its reinvented "K2" mission,
are highlighted in this sped-up movie. The planet Neptune appears on
day 15, followed by its moon Triton, which looks small and faint.
Keen-eyed observers can also spot Neptune's tiny moon Nereid at day 24.
Neptune is not moving backward but appears to do so because of the
changing position of the Kepler spacecraft as it orbits around the sun. Credits: NASA Ames/SETI Institute/J. Rowe
NASA's Kepler spacecraft, known for its planet-hunting prowess of other stars, is also studying solar system objects. In its new K2 mission, Neptune and two of its moons, Triton and Nereid, have been imaged. The movie illustrates 70 days of uninterrupted observation making this one of the longer continuous studies of an outer solar system object.
The movie, based on 101,580 images taken from November 2014 through
January 2015 during K2's Campaign 3, reveals the perpetual clockwork of
our solar system. The 70-day timespan is compressed into 34 seconds with
the number of days noted in the top right corner.
Neptune appears on day 15 but does not travel alone in the video.
The small faint object closely orbiting is its large moon Triton, which
circles Neptune every 5.8 days. Appearing from the left at day 24,
keen-eyed observers can also spot the tiny moon Nereid in its slow
360-day orbit around the planet. A few fast-moving asteroids make cameo
appearances in the movie, showing up as streaks across the K2 field of
view. The red dots are a few of the stars K2 examines in its search for
transiting planets outside of our solar system.
Neptune's atmosphere reflects sunlight creating a bright appearance.
The reflected light floods a number of pixels of the spacecraft's on
board camera, producing the bright spikes extending above and below the
planet. The celestial bodies in the stitched-together images are colored
red to represent the wavelength response of the spacecraft's camera. In
reality, Neptune is deep blue in color and its moons and the speeding
asteroids are light grey while the background stars appear white from a
distance.
Relative orbit speeds explain the interesting motion of Neptune and
its moons beginning at day 42. Inner planets like Earth orbit more
quickly than outer planets like Neptune. In the movie, Neptune’s
apparent motion relative to the stationary stars is mostly due to the
circular 372-day orbit of the Kepler spacecraft around the sun. If you
look at distant objects and move your head back and forth, you will
notice that objects close to you will also appear to move back and
forth, relative to objects far away. The same concept is producing the
apparent motion of Neptune.
While NASA’s Kepler spacecraft is known for its discoveries of
planets around other stars, an international team of astronomers plans
to use these data to track Neptune’s weather and probe the planet’s
internal structure by studying subtle brightness fluctuations that can
only be observed with K2.
NASA's Ames Research Center in Moffett Field, California, manages the
Kepler and K2 missions for NASA’s Science Mission Directorate. NASA's
Jet Propulsion Laboratory in Pasadena, California, managed Kepler
mission development. Ball Aerospace & Technologies Corp. operates
the flight system with support from the Laboratory for Atmospheric and
Space Physics at the University of Colorado in Boulder.
