Buy the Hubble Springtime on Neptune space photo. High quality Hubble picture, slide, or Duratrans backlit transparency. NASA photograph H2003-17d . Wide variety of sizes. Click to see selection as Astronomy Picture of the Day (APOD) - June 26, 2004 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. May 15, 2003 Credit: NASA, L. Sromovsky, and P. Fry (University of Wisconsin-Madison) |