Illustration of Saturn. Image: Vadim Sadovski/Shutterstock
Saturn and its famous rings have been studied for decades, but new discoveries have been made that prove there is much more than what we can see.
The exact origin of the rings of Saturn has perplexed astronomers for centuries, but, using the latest technology, the pieces of puzzle are gradually being put together.
A team of researchers in Japan has analysed mid-infrared images taken by the Subaru Telescope in 2008 – the highest-resolution ground-based views ever made – to unlock new secrets behind what makes the rings tick.
By analysing images taken by the telescope using its Cooled Mid-Infrared Camera and Spectrometer (COMICS), the team noticed some peculiar differences between how we see the rings in visible light, and how we see them in mid-infrared.
Saturn’s rings are typically separated into three different sections: A, B and C, with the gap between B and A referred to as the Cassini Division.
In the mid-infrared spectrum, the Cassini Division and C are shown to be much brighter than either A or B, completely opposite to how the rings appear in visible light.
Based on the team’s analysis, this reversal indicates that thermal emissions are much greater in C and the Cassini Division because they are more easily heated by solar light due to their sparser populations and darker surfaces.
A three-colour composite of the mid-infrared images of Saturn on 23 January 2008, captured with COMICS on the Subaru Telescope. Colour differences reflect the temperatures; the warmer part is blue, the cooler part is red. Image: NAOJ
Seasonal differences
During observation in the visible light spectrum, B and A appear brighter because they are densely packed with particles that reflect more light.
However, just to make things more complicated, it turns out that the Cassini Division and the C ring are not always brighter than the B and A rings, even in the mid-infrared, as images from 2005 showed fainter emissions.
After some calculations, it was concluded that the inversion of the brightness of Saturn’s rings between 2005 and 2008 was caused by the seasonal change in the ring opening angle to the sun and Earth.
The culmination of this research has been the creation of an incredible, colourful image of Saturn in the mid-infrared.
“We are going to observe Saturn again in May 2017 and hope to investigate the nature of Saturn’s rings further by taking advantages of observations with space missions and ground-based telescopes,” said lead researcher Dr Hideaki Fujiwara.
The team’s research has now been published in the journal Astronomy & Astrophysics.
Updated, 4.49pm, 27 February 2017: This article was amended to provide the correct surname for Dr Hideaki Fujiwara.
