Featured Research

from universities, journals, and other organizations

When it rains, it pours ... on the sun

Date:
June 24, 2014
Source:
Royal Astronomical Society (RAS)
Summary:
Just like on Earth, the sun has spells of bad weather, with high winds and showers of rain. But unlike storms on Earth, rain on the sun is made of electrically charged gas (plasma) and falls at around 200,000 kilometers an hour from the outer solar atmosphere, the corona, to the sun's surface. Now a team of solar physicists has pieced together an explanation for this intriguing phenomenon with imagery that shows a 'waterfall' in the atmosphere of the sun.

A mosaic of images obtained using the Swedish Solar Telescope (SST), revealing evidence of a large-scale coronal rain shower pouring relentlessly into the dark sunspot on the surface of the Sun. The coronal rain shower appears as the labelled giant arching water-fall-like flow. At the top left the Earth is depicted on the same scale.
Credit: E. Scullion / SST

Just like on Earth, the Sun has spells of bad weather, with high winds and showers of rain. But unlike the all-too-frequent storms of the UK and Ireland, rain on the Sun is made of electrically charged gas (plasma) and falls at around 200,000 kilometres an hour from the outer solar atmosphere, the corona, to the Sun's surface. And the thousands of droplets that make up a 'coronal rain' shower are themselves each as big as Ireland.

Now a team of solar physicists, led by Dr Eamon Scullion of Trinity College Dublin, has pieced together an explanation for this intriguing phenomenon, with imagery that shows a 'waterfall' in the atmosphere of the Sun. Dr Scullion will present their work at the National Astronomy Meeting (NAM 2014) in Portsmouth on Tuesday 24 June 2014.

Discovered almost 40 years ago, solar physicists are now able to study coronal rain in great detail thanks to state-of-the-art satellites like the NASA Solar Dynamics Observatory (SDO) and ground-based observatories like the Swedish 1-m Solar Telescope (SST). The scientists see regular and massive shifts in the solar 'climate', but despite decades of research have until now been unable to understand the physics of coronal rain.

It turns out that the process through which hot rain forms on the Sun is surprisingly similar to how rain happens on Earth. If the conditions in the solar atmosphere are just right, then clouds of hot, dense plasma can naturally cool and condense and eventually fall back to the solar surface as droplets of coronal rain.

In another parallel with terrestrial weather, the material that makes up the hot rain clouds reaches the corona through a rapid evaporation process. But here the evaporation is caused by solar flares, the most powerful explosions in the Solar system that are thought to help heat the Sun's outer atmosphere.

The torrential rain storms, driven by solar flares, may play a fundamental role in controlling the mass cycling of the solar atmosphere and act as a kind of "solar-scale" thermostat in regulating the temperature fluctuations of the solar corona. The origins of solar coronal heating remains one of the longest standing puzzles in solar physics.

Dr Scullion and his team have now developed a new insight into how coronal rain forms. Together with collaborators in Trinity College Dublin and the University of Oslo in Norway, he suggests a model of 'catastrophic cooling', where an exceptionally rapid fall in temperature causes material to change from rarefied coronal gas to 'raindrops'.

The team used images from the Swedish Solar Telescope (SST) based on La Palma in the Canary Islands, a telescope that produces some of the sharpest images of the Sun available. In June 2012 they observed a giant 'waterfall' of solar material pouring down from the outer atmosphere of the Sun into a dark sunspot on its surface. Another set of images have been assembled into a movie and show how a solar flare precedes a 'rain shower'.

Dr Scullion comments: "Showers of 'rain' and waterfalls on the Sun are quite something, though I wouldn't recommend taking a stroll there anytime soon. But the parallels with weather on Earth are both striking and surprising."


Story Source:

The above story is based on materials provided by Royal Astronomical Society (RAS). Note: Materials may be edited for content and length.


Cite This Page:

Royal Astronomical Society (RAS). "When it rains, it pours ... on the sun." ScienceDaily. ScienceDaily, 24 June 2014. <www.sciencedaily.com/releases/2014/06/140624093244.htm>.
Royal Astronomical Society (RAS). (2014, June 24). When it rains, it pours ... on the sun. ScienceDaily. Retrieved September 15, 2014 from www.sciencedaily.com/releases/2014/06/140624093244.htm
Royal Astronomical Society (RAS). "When it rains, it pours ... on the sun." ScienceDaily. www.sciencedaily.com/releases/2014/06/140624093244.htm (accessed September 15, 2014).

Share This



More Space & Time News

Monday, September 15, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA’s Curiosity Rover Finally Reaches Long-Term Goal

NASA’s Curiosity Rover Finally Reaches Long-Term Goal

Newsy (Sep. 15, 2014) — After more than two years, NASA’s Mars Curiosity Rover reached Mount Sharp, its long-term destination. Video provided by Newsy
Powered by NewsLook.com
SpaceX's Elon Musk Really Wants To Colonize Mars

SpaceX's Elon Musk Really Wants To Colonize Mars

Newsy (Sep. 14, 2014) — Elon Musk has been talking about his goal of colonizing Mars for years now, but how much of it does he actually have figured out, and is it possible? Video provided by Newsy
Powered by NewsLook.com
International Space Station Crew Returns Safely To Earth

International Space Station Crew Returns Safely To Earth

Newsy (Sep. 11, 2014) — The three-man crew touched down in Kazakhstan Wednesday after more than five months of science experiments in orbit. Video provided by Newsy
Powered by NewsLook.com
Solar Storm To Hit This Weekend, Scientists Not Worried

Solar Storm To Hit This Weekend, Scientists Not Worried

Newsy (Sep. 11, 2014) — Two solar flares which erupted in our direction this week will arrive this weekend. The resulting solar storm will be powerful but not dangerous. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins