The Sun has been gradually getting hotter for the past seven years, as part of its 11-year solar cycle, according to a new study.
For the first time, changes in the temperature of the Sun's hot atmosphere, the corona, have been studied over a timescale of years.
“To do this, we analysed Extreme Ultraviolet radiation emitted by the corona, and measured by the Atmospheric Imaging Assembly telescopes aboard the Solar Dynamic Observatory spacecraft,” Huw Morgan, from Aberystwyth University and lead author of the study, told WIRED.
Studying the solar coronais important for understanding what drives the solar cycle, how this cycle affects light and heat output by the Sun, and how cycle-related changes may affect Earth.
This new paper is a step towards being able to predict space weather, likesolar storms, which Morgan expects will be possible within the next couple of decades.
“Many important aspects of the Sun, and its connection with the corona and space weather, are poorly understood,” Morgan told WIRED.
“Yet with each new observing mission, and advances in computer modelling, we are moving closer to understanding this complex system. This study is another small piece of the jigsaw.”
The authors took what they described as a 'brute force' approach, analysing several hundred thousands of images in order to estimate the mean temperature of the Sun from mid-2010 to this year.
The corona of the Sun is hot, more than a million degrees to be exact.
“The most exciting finding in the study is the gradual yet consistent increase in the corona's mean temperature between 2010 and present, from 1.4 to 1.8 million degrees,” Morgan told WIRED.
This rise is linked to the solar cycle, since during the solar cycle, the number of 'sunspots' increase.
Sunspots are small regions of intense magnetic field which have recently surfaced from the Sun's interior. They cause 'active regions' in the corona, which are very hot and dense.
Over periods of weeks or months, these active regions gradually decay. But in doing so, they are forcing the global mean temperature of the corona to increase.
The paper is published in the journal Science Advances.
This article was originally published by WIRED UK
