Find us on Google+

Seven Years of Tracking the Solar Cycle

Our sun is ever-changing, and a satellite called
the Solar Dynamics Observatory has a front-row seat. 

image

On February 11, 2010, we launched the Solar Dynamics
Observatory, also known as SDO. SDO keeps a constant eye on the sun, helping us
track everything from sunspots to solar flares to other types of space weather
that can have an impact on Earth.

After seven years in space, SDO has had a chance to do what few
other satellites have been able to do – watch the sun for the majority of a
solar cycle in 11 types of light.

image

The sun’s activity rises and falls in a pattern that lasts
about 11 years on average. This is called the solar cycle.

Solar activity can influence Earth. For
instance, it’s behind one of Earth’s most dazzling natural events – the aurora.

image

One of the most common triggers of the aurora is
a type of space weather called a coronal mass ejection, which is a billion-ton
cloud of magnetic solar material expelled into space at around a million miles
an hour. 

image

When these clouds collide with Earth’s magnetic field, they
can rattle it, sending particles down into the atmosphere and triggering the
auroras. These events can also cause satellite damage and power grid strain in
extreme cases. 

The sun is in a declining activity phase, so coronal mass
ejections will be less common over the next few years, as will another one of
the main indicators of solar activity – sunspots.

image

Sunspots are created by twisted knots of magnetic field. Solar
material in these tangled regions is slightly cooler than the surrounding areas,
making them appear dark in visible light.

image

The tangled magnetic field that creates sunspots also causes
most solar activity, so more sunspots means more solar activity, and vice
versa. Humans have been able to track the solar cycle by counting sunspots
since the 17th century.  

image

Image: Houghton Library, Harvard University,
*IC6.G1333.613ia

The peak of the sun’s activity for this cycle,
called solar maximum, was in 2014. 

image

Now, we’re heading towards the lowest solar
activity for this solar cycle, also known as solar minimum. As solar activity
declines, the number of sunspots decreases. We sometimes go several days
without a single visible sunspot.

image

But there’s much more to the story than sunspots
– SDO also watches the sun in a type of light called extreme ultraviolet. This
type of light is invisible to human eyes and is blocked by our atmosphere, so
we can only see the sun this way with satellites.

image

Extreme ultraviolet light reveals different layers of the
sun’s atmosphere, helping scientists connect the dots between the sunspots that
appear in visible light and the space weather that impacts us here on Earth.

SDO keeps an eye on the sun 24/7, and you can see near real-time
images of the sun in 11 types of light at sdo.gsfc.nasa.gov/data.

Source: NASA

by
Seven Years of Tracking the Solar Cycle

Posted in NASA and tagged by with no comments yet.

Leave a Reply

Your email address will not be published. Required fields are marked *