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News Release 79 of 181

May 15, 2003 09:00 AM (EDT)

News Release Number: STScI-2003-17

Brighter Neptune Suggests a Planetary Change of Seasons

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Image: Springtime on Neptune: Increased Brightness Shows Seasonal Change

Springtime on Neptune: Increased Brightness Shows Seasonal ChangeSTScI-PRC2003-17

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NASA Hubble Space Telescope observations in August 2002 show that Neptune's brightness has increased significantly since 1996. The rise is due to an increase in the amount of clouds observed in the planet's southern hemisphere. These increases may be due to seasonal changes caused by a variation in solar heating. Because Neptune's rotation axis is inclined 29 degrees to its orbital plane, it is subject to seasonal solar heating during its 164.8-year orbit of the Sun. This seasonal variation is 900 times smaller than experienced by Earth because Neptune is much farther from the Sun. The rate of seasonal change also is much slower because Neptune takes 165 years to orbit the Sun. So, springtime in the southern hemisphere will last for several decades! Remarkably, this is evidence that Neptune is responding to the weak radiation from the Sun. These images were taken in visible and near-infrared light by Hubble's Wide Field and Planetary Camera 2.

Object Name: Neptune

Image Type: Astronomical/Annotated

Credit: NASA, L. Sromovsky, and P. Fry (University of Wisconsin-Madison)

NEWS RELEASE IMAGES

The above montage includes these images:

Springtime on Neptune — 1996 Image of Neptune Image Type: Astronomical Springtime on Neptune — 1996 Image of Neptune Springtime on Neptune — 1998 Image of Neptune Image Type: Astronomical Springtime on Neptune — 1998 Image of Neptune Springtime on Neptune — 2002 Image of Neptune Image Type: Astronomical Springtime on Neptune — 2002 Image of Neptune

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