SETI Institute Principal Investigator
In the outskirts of our solar system, the planets Uranus and Neptune are far from the warming rays of the Sun. Similar to one another in size, about four times the diameter of Earth, both of these planets have a rocky core, an icy mantle, and an atmosphere of hydrogen and helium. Why then is Uranus cloaked in a monotonous, blue-tinged atmosphere, while Neptune’s dynamic atmosphere contains such prominent features as the Great Dark Spot and its Bright Companion? The critical difference between these two planets, according to astronomer Kathy Rages, is that much more heat emerges from Neptune’s interior than from the core of Uranus. Neptune gets only a thousandth as much sunlight as the Earth does, but Neptune’s internal heat powerfully energizes its atmosphere.
As Rages tries to understand why such similar planets have such different internal temperatures, she draws on observations from the Hubble Space Telescope. These images show a great increase in the atmospheric activity on Uranus over the past decade, corresponding to the changing seasons on Uranus. Rages will also be studying the Hubble data to see whether there’s a connection between the inner heating of Uranus and the severe tilt of its axis, which undoubtedly leads to extreme seasons.
- SETI Institute Explorer, Special Edition 2005