Neptune and Uranus
are so similar that scientists sometimes refer to the distant, icy planets as planetary twins.
But these ice giants
have one big difference: their color. Neptune has a bright blue appearance. Uranus is a paler shade of cyan blue.
New space and
ground-based telescope observations have revealed what's behind this difference in tone.
The difference was spotted
only when NASA's Voyager 2 spacecraft flew by them in the 1980s and two planets were compared side by side
Astronomers used the
Hubble Space Telescope to create a model that could match up observations of Neptune and Uranus.
Excess of haze builds up
in Uranus' atmosphere, which gives it a lighter appearance. This haze is thicker on Uranus than a similar atmospheric layer on Neptune