This image from Hubble Space Telescope is NGC 1637, a spiral galaxy located 38 million light-years from Earth in the constellation Eridanus (Photo – esahubble)
From 2014 to 2024, the NASA/ESA Hubble Space Telescope has been studying the outer planets under a program called OPAL (Outer Planet Atmospheres Legacy).
By News Desk
OPAL is used to obtain long-time baseline observations of Jupiter, Saturn, Uranus, and Neptune in order to understand their atmospheric dynamics and evolution. Hubble is the only telescope that can provide high spatial resolution and image stability for global studies of cloud coloration, activity, and atmospheric motion on a consistent time basis to help constrain the underlying mechanics of weather and climate systems.
Highlights of the OPAL team’s decade of discovery:
– Jupiter
Hubble’s sharp images track clouds and measure the winds, storms, and vortices, in addition to monitoring the size, shape and behavior of the GRS.
OPAL’s findings may also support ESA’s Jupiter Icy Moons Explorer, Juice, which was launched on 14 April 2023. Juice will make detailed observations of Jupiter and its three large ocean-bearing moons — Ganymede, Callisto and Europa.
– Saturn
Saturn takes more than 29 years to orbit the Sun, and so OPAL has followed it for approximately one quarter of a Saturnian year (picking up in 2018, after the end of the Cassini mission).
Saturn’s mysteriously dark ring spokes, which slice across the ring plane, are transient features that rotate along with the rings. Hubble shows that the frequency of spoke apparitions is seasonally driven, first appearing in OPAL data in 2021. Long-term monitoring shows that both the number and contrast of the spokes vary with Saturn’s seasons.
– Uranus
With OPAL, Hubble first imaged Uranus after the spring equinox, when the Sun was last shining directly over the planet’s equator. Hubble resolved multiple storms with methane ice-crystal clouds appearing at mid-northern latitudes as summer approaches the north pole.
– Neptune
When Voyager 2 flew by Neptune 1989, astronomers were mystified by a great dark spot the size of the Atlantic Ocean looming in the atmosphere. Was it long-lived like Jupiter’s Great Red Spot? The question remained unanswered until Hubble was able to show in 1994 that such dark storms were transitory, cropping up and then disappearing over a duration of two to six years each. During the OPAL program, Hubble saw the end of one dark spot and the full life cycle of a second one – both of them migrating toward the equator before dissipating.
Hubble observations uncovered a link between Neptune’s shifting cloud abundance and the 11-year solar cycle. Do the planet’s four seasons (each lasting approximately 40 years) also play a role? We may find out, if the OPAL program continues running on Hubble until the year 2179!
Source: esahubble.
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