Space and astronomy news
This week, we’re on to the next planet in the solar system. Having only visited it up close once with Voyager 1, we don’t know much about this sideways-spinning ice giant. But today we’ll cover what we do know, including its faint rings, sideways axis of rotation and rocky core – a first in the gas planets we’ve encountered so far in our tour.
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Uranus – Show notes and transcript
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Once every 42 years, the angle between Uranus and the Earth is perfectly lined up so that the planet’s rings are seen edge on. Since the rings were only discovered back in 1977, this is the first opportunity astronomers will have to view the planet without the glare and dust from the rings. It doesn’t happen on a specific date, though, it’s a little more complicated than that.
Because the Earth goes around the Sun much more quickly than Uranus, there are actually three separate times that Uranus and the Earth line up perfectly: May 3 and August 16 in 2007, and then February 20 in 2008. Unfortunately, during that last point, the Sun will be directly in between our two planets, so we won’t be able to see Uranus.
The first to image Uranus during this special occasion was a team of astronomers from UC Berkeley. They imaged Uranus on May 28th with the near infrared camera and adaptive optics on the W.M. Keck II telescope atop Hawaii’s Mauna Kea. Their images revealed the nearly edge on ring appearing as a bright line passing right through Uranus.
The next images come from Hubble, taken on August 14th. Hubble captured its images on nearly the precise moment when the rings were aligned with the Earth, showing similar features to the Keck image, and also seeing some recently discovered outer rings. The outermost ring, seen by Hubble, is difficult to view in infrared.
Astronomers are hoping these images will reveal more details about the moons that help tend the ring, called Cordelia and Ophelia, keeping it in place. But it’s also thought that there are additional moons in the region, helping to tend all 9 rings. This precise geometry might allow the telescopes to reveal moons that would normally be lost in the glare of the rings.
One other important date:
“December 7 is the Uranian equinox, when the rings are perfectly edge-on to the sun, and after that, there is a brief period again when we will view the dark side of the rings, before they become illuminated again for another 42 years,” said Heidi B. Hammel of the Space Science Institute in Boulder, Colorado.
Original Source: UC Berkeley News Release
The Hubble Space Telescope has discovered a giant cloud vortex in the upper atmosphere of Uranus. This cloudy feature measures 1,700 kilometers by 3,000 kilometers (1,100 miles by 1,900 miles) – large enough to engulf 2/3rd of the US. Although rare on Uranus, these cloud spots are actually quite common on Neptune, since the ice planet has a much more active atmosphere. Since this region of Uranus’ atmosphere was previously in shadow, astronomers theorize that heat from the sun created the vortex.
Continue reading “Dark Spot in Uranus’ Clouds”
The Hubble Space Telescope recently captured a very rare event: the transit of its moon Ariel across the surface of Uranus. On Earth we call this an eclipse, when the Moon’s shadow falls upon the surface of our planet. This situation is rare on Uranus; however, because the blue-green planet is tilted over on its side. The Sun, the moons and Uranus only line up once every 42 years. The last time a transit like this could have been seen was 1965, but Earth-based telescopes weren’t powerful enough to image the event at the time.
Continue reading “Hubble Sees a Rare Transit on Uranus”