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In Tune with Neptune
Release Date: July 27, 2010
The New Horizons Long Range Reconnaissance Imager (LORRI) observed Neptune on June 23, apl2010, as part of a test of the critical optical navigation Annual Checkout (ACO)-4. In this 100-millisecond exposure, taken when the spacecraft was 23.2 astronomical units (about 2.15 billion miles) from Neptune, the planet appears slightly larger than a star. At the time of this observation, the solar phase angle (the spacecraft-planet-Sun angle) was 34 degrees and the solar elongation angle (planet-spacecraft -Sun angle) was 95 degrees. Only New Horizons can observe Neptune at such large solar phase angles, which can be used to study the light-scattering properties of Neptune's atmosphere.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute