Summer storms finally appeared on Uranus, seven years after the planet reached its closest approach to the Sun, leaving scientists with a riddle of why massive storms arose so late.
“Usually, the quiet gas giant currently has incredibly active weather. Some of these weather formations are visible even to amateurs,” said Imke De Pater, lead project researcher and astronomer at the University of California, Berkeley. Astronomers first announced the discovery of a storm on Uranus in August.
This is by far the most active weather that the team of Imke De Patera has observed on Uranus over the past decades, considering the storms and the northern convective features of the planet. She also paints a different picture of a quiet planet that Voyager 2 saw when, when NASA's spacecraft flew to her in 1986.
"We expected to see such activity in 2007, when Uranus had an equinox recurring every 42 years and the Sun shone directly at the equator," said co-investigator Heidi Lamu of the Association of Universities for Astronomy Research in a statement. "Why we see these storms just now, remains a mystery to us."
But here is where the secret lies: to what extent can we say, Uranus does not have a source of internal heat. Sunlight is believed to be responsible for changes in its atmosphere, such as storms. But sunlight is currently rather weak in the northern hemisphere of Uranus, so scientists are wondering why this area is so active today. De Patera’s team is currently tracking a storm in the northern hemisphere of Uranus, observing the planet with the Keck II telescope. One storm stood out from the rest: shining at 2.2 microns, it accounts for 30 percent of all light reflected from Uranus.
Another storm of 1, 6 microns, may even be seen by amateur astronomers. One observer, Mark Delacroix from France, photographed it with a 1-meter telescope.
"I was excited when I saw such activity on Uranus," said Delacroix in a statement from the Keck Observatory. “Obtaining information about Mars, Jupiter or Saturn is something routine for us. But observing in such detail the formations on Uranus or Neptune opens up new frontiers for us, and I didn’t want to miss it.”
Based on the color and structure of the storm seen by amateurs, professional astronomers believe that a storm is like a whirlwind deep in the atmosphere of the planet. For example, by analogy with the phenomena seen on Jupiter, the Great Red Spot.
Subsequent observations with the Keck II telescope showed that the storm was still raging, although it changed its shape and, perhaps, its intensity.
The Hubble Space Telescope, which examined the entire planet on October 14 at several wavelengths, made a huge contribution to this observation. Observations have shown that a storm covers several heights, at a distance of up to 5592 miles (9000 kilometers).