Springtime on Neptune: Images hint at seasonal changes on distant planet
By Ron Cowen
Belying its location in the deep freeze of the outer solar system, Neptune is anything but dormant. It sports giant storms and near-supersonic winds. Now, images taken by the Hubble Space Telescope indicate that this frigid ball of gas, which receives only 0.1 percent as much sunlight as Earth does, even undergoes a change of seasons. If Larry A. Sromovsky of the University of Wisconsin-Madison and his colleagues are correct, it’s now spring on Neptune’s southern hemisphere.
Visible-light images taken by the team with Hubble in 1996, 1998, and 2002 show that a band of clouds encircling the planet’s southern hemisphere has grown larger and brighter, the researchers report in the May Icarus. The findings are consistent with ground-based pictures taken since 1972 by G. Wesley Lockwood of the Lowell Observatory in Flagstaff, Ariz. Recent near-infrared observations also hint at increased cloud cover on Neptune, Sromovsky’s team notes.