Hi, I'm Joe Gurman, I'm a solar physicist in
the heliophysics division at NASA's Goddard Space Flight Center.
All of the eight large planets in the solar system orbit the Sun
in a plane that lies within a few degrees of the Earth's
orbital plane, the so-called ecliptic. So when we observe the Sun with a coronagraph,
that blocks the much brighter light from the Sun itself so we can see the faint
corona, the Sun's hot, outermost atmosphere, we get occasional
glimpses of planets. And in this remarkable series of
images, we actually get to see several different planets. And also in the upper-left
of the image, you can see the Pleiades, the star cluster. The images of the
planets come out here looking as though they have horizontal streaks,
because they're so bright that they overwhelm the
electronics in the detector that's taking this image. SOHO's
Extreme Ultraviolet Telescope allows us to see a variety of solar activity
and some of the most intense activity we saw was in the fall of 2003.
It was a bit of a surprise because it was a couple of years after the maximum, the 11-year
solar activity cycle. It's a beautiful clip, and it shows what SOHO's Extreme
Ultraviolet Telescope can do. So what we're seeing here is those same
periods of activity in the fall of 2003, only this
time from SOHO's coronagraph. And you can see a sequence of events,
so-called coronal mass ejections, launching off in all directions
as the active region rotates across the solar
surface. And you also see what looks like snow on the windshield
of a car driving through a blizzard, and that's energetic particles
accelerated by the solar activity hitting the detectors
on the SOHO spacecraft.
Prominences are cooler gas that flows along magnetic fields
in the much hotter solar corona. And this image from 1999
you can see the eruption of a huge prominence from a fairly high latitude
in the Sun, and that tells us that it's associated with new cycle
magnetic fields and with the expulsion of twists in
magnetic fields from the old solar cycle.
Each of those approximately 11-year halves of the magnetic cycle
displays its own cycle of first increasing and then decreasing
magnetic activity, and that's reflected in the intensity
of extreme ultraviolet emission from gas that's trapped in
the magnetic field. So in this image you can see a series
of snapshots taken one a year over
a solar cycle.
Over the course of the SOHO
mission, we've observed over 3,000 sun-grazing comets, comets that come
so close to the Sun that you can't see them from the Earth because the Sun basically
blinds Earth-bound telescopes. With SOHO's coronagraphs, we're able to track
the comets all the way into their evaporation near the Sun.
In late 2012, astronomers discovered
a comet inbound, we didn't know if it would survive its passage with the Sun or not,
and we were able to get these measurements with SOHO's C3 coronagraph.
of the comet as it passed
in towards the Sun, and then the ghostly image of the comet continued
past the Sun, but it was already evaporating.
If you're able to catch it, and if you blink you'll miss it, you see a wave
traveling outwards from the flare in the lower solar corona
EIT was really good at, and in fact discovered, these waves in the very
lowest part of the corona that corresponded to coronal mass ejections, and we literally
hadn't known about that before. In a coronagraph, you don't know if an event
is heading towards you or away from you, the geometry is the same. And
with the addition of an extreme ultraviolet image,
that shows a wave like this, then you know that the event has occurred on
the Earthward side of the Sun, and we may very well have some space weather in store
in one to three days. This clip shows Comet Machholz
which SOHO observed in 2002 as it was passing near the Sun. And
as the clip shows, the direction of the comet's tail, which
is made up of electrically charged particles, changes as it passes the Sun,
that's because the Sun's solar wind, a continual emission of plasma
from the Sun, is pushing it outwards.
This shows an entire solar rotation of about 28 days.
In 2001, as we were ascending up to solar maximum,
and you'll see several events in here, and the interesting
thing about these is how they're distributed in latitude, they're not all
just along the horizontal axis in this series of images.
And that's an indication that you are reaching solar maximum.
During solar minimum, the much smaller number of events that happen
all seem to come off the east or west edges of the Sun. But as you get toward
solar maximum, the active regions are distributed all over in latitude.
And you get this much more active appearance.
[spacecraft whooshes by] [beep beep, beep beep]
[beep beep, beep beep, beep beep]