- Hubble took amazing pictures of Saturn featuring its fluttering aurora at the north pole.
- The images were captured in UV light and readings were coordinated with Cassini spacecraft.
- This helped researchers know more about Saturn’s magnetosphere.
The Hubble Space Telescope has extensively observed the auroras of Saturn in the far-ultraviolet wavelength using Advanced Camera for Surveys and Space Telescope Imaging Spectrograph. A large amount of data obtained from these observations has been coordinated with Cassini’s measurement (a spacecraft studying Saturn and its system).
In 2004, Hubble analyzed Saturn’s southern auroras right after southern solstice (an event that occurs when the Sun reaches its highest position in the sky as seen from the Saturn’s south pole). In 2009, Hubble recorded Saturn when its rings were edge-on, which allowed it to observe both of the Saturn’s pole and their auroras at the same time.
Over the 7-months duration in 2017, Hubble took pictures of auroras of Saturn’s north pole area. To achieve the best observations, these pictures were captured before and after the northern summer solstice.
How Auroras Are Formed?
On our planet, auroras are formed by solar-wind particles emitted by the Sun. They are electrically charged particles that interact with Earth’s magnetic field. While this massive field is known for protecting the environment of Earth from particles emitted by the Sun, it also traps a small amount of electrically charged particles.
The Earth’s magnetosphere traps these particles, which then follow the magnetic lines down to the magnetic poles. Then they collide with atoms and molecules in our atmosphere, resulting in countless small bursts of light, or photons, that make up the aurora.
Collisions with nitrogen generate the purple and pink colors, while oxygen produces green and red auroras, at an altitude of 65 to 650 kilometers in a zone known as Auroral Oval.
Similar types of auroras have been found on other planets as well. The 4 our those planets in our solar system are Neptune, Uranus, Saturn, and Jupiter. Unlike Earth, the atmosphere of these 4 planets mainly consists of hydrogen. Thus, auroras of these planets can only be observed in ultraviolet wavelengths by space-based telescopes.
Saturn’s Energetic Light Show
Saturn’s Northern auroras observed in UV light | Credit: ESA/NASA Hubble
The Hubble Space Telescope made it possible to closely investigate the behavior of Saturn’s north pole auroras over a longer period of time. These readings were coordinated with Cassini’s Grand Finale (the thrilling part of spacecraft’s 2-decade-long story of exploration) when it probed the Saturn’s Auroral Oval.
After collecting the stunning pictures and new data of Saturn, Cassini was safely crashed into Saturn on 15th September 2017. Both Cassini and Hubble enabled researchers to uncover more details of Saturn’s magnetosphere.
The images reveal a wide range of emissions with variable localized features. This variability lasts only 11 hours, and it’s mainly caused by Saturn’s rotational speed and solar wind particles.
Image credit: ESA/NASA Hubble
The above image is created by analyzing all observations made in early 2018 in the optical, and Saturn’s northern auroras observed in 2017. The picture clearly demonstrates the size of auroras along with planet’s vibrant colors.
The aurora shows 2 different brightness peaks. The first one occurs at dawn and right before midnight, while the second peak (observed first time in history) was specific to the interaction between Saturn’s magnetosphere (at solstice) and solar wind.