This video is sponsored by MagellanTV. The European Space Agency released
the first images from the Solar Orbiter spacecraft. These are the
closest images of the Sun ever taken and reveal details that have never been
seen before. But though these images were only taken to test the spacecraft’s
instruments, they are already hinting at a possible answer to a mystery that has
puzzled astronomers for over 150 years. Welcome back to Launch
Pad, I’m Christian Ready, your friendly neighborhood astronomer. ESA’s Solar Orbiter began its journey
to the Sun when it lifted off from Cape Canaveral on February 9,
2020 at 11:03 PM local time. Its mission is to make the most
comprehensive study of the Sun. It does this with a battery of
instruments to study the Sun’s atmosphere, corona, solar wind, and
magnetic fields. Its imaging system has already provided the closest
images ever taken of the Sun, and will make the first ever
direct images of the Sun’s poles. All of this is critical for
understanding how the Sun drives space weather and how solar storms
directly affect our home planet. In fact, there’s a great documentary
about Solar Superstorms available on MagellanTV, who are very
kindly sponsoring today’s video. Solar Superstorms takes you to the
Sun’s surface to witness the solar flares and coronal mass ejections which
can pose a threat to our satellites, electronics, and electrical
grids. It's just one of many documentaries on the Sun and other
topics available on MagellanTV. Magellan is a new type of streaming
service that brings together documentaries on nature, history,
art, and of course my favorites, space and science. New titles are
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from your mobile device to your TV. Documentaries are streamed
without interruptions, ads, or limitations to access. And that
includes a wide selection of programs available in beautiful
4K, at no additional cost. If you enjoy the content here on Launch
Pad Astronomy, then I think you’re really going to like MagellanTV as well.
To that end, MagellanTV are offering a free, month-long introductory
trial offer for my viewers. Please visit the link on your screen to
take advantage of this special offer. You’ll find the link in the
description of this video. After separating from
the Atlas V booster, Solar Orbiter deployed its solar arrays, antennae, and instrument booms. It
then begin its commissioning period. This is when the science instruments are
turned on, checked out, and calibrated. Normally this would be done with
everyone working at ESA’s Operations Center. However, the UK and most
of the EU countries imposed strict stay at home orders early on in the
outbreak of the novel coronavirus. So, Solar Orbiter became ESA's first spacecraft to be commissioned
largely from people’s homes. As part of its commissioning,
test images of the Sun were made in May during Solar Orbiter’s
first perihelion; that is, it’s first close approach to the Sun. At
the time, the spacecraft was 77 million km away from the Sun, which is about
half of Earth’s distance. Even though these were just test images, they
revealed details never seen before. These images were taken with
the Extreme Ultraviolet Imager. It images the Sun’s outer
atmosphere, called the corona. Throughout the images are what appear to
be tiny flares dubbed "campfires". These flares appear just beneath the corona,
near the Sun’s surface. They seem like miniature versions of the large
solar flares that we see form Earth. From this distance, each pixel
corresponds to about 400 km, so these campfires are still large by
Earth standards. But the fact they’re showing up in these test images when
the Sun is so quiet is quite surprising. You see, the Sun undergoes an
11-year cycle of magnetic activity. It starts out with a largely
stable magnetic field. But as the Sun rotates, its
magnetic field gets tangled. This leads to sunspots, flares,
and even coronal mass ejections. Right now, there’s very little magnetic
activity so we are experiencing a "quiet" Sun. But these
images show that even a "quiet" Sun is remarkably active.
producing the same features we see during active periods, but
on a much smaller scale. Like I said, these were just tests to make sure the cameras are working.
They’re not the science-quality images that we’ll get when Solar
Orbiter gets closer. But these campfires hint at a possible answer
to the mystery of the Sun’s corona. Even though the corona is the Sun’s
upper atmosphere, temperatures there are about a million degrees hotter than
at the surface! That makes no sense. It’s like raising your hand away from a
hot stove and suddenly getting burned. This phenomenon was first noticed
in 1869 and scientists have been trying to figure out the
reason for it ever since. One long-held theory is
that there could be small "nano-flares” continuously
erupting in the quiet corona. In the nano flare hypothesis,
local regions of the Sun’s magnetic field become entangled due
to convection in the Sun’s surface. Electrically charged particles
- or plasma - get trapped in the magnetic field lines. As the magnetic
field lines become further entangled, they come together and snap
apart like rubber bands, unleashing a flare of energized
plasma. This is called 'magnetic reconnection' and is the mechanism at
the heart of all explosions on the Sun. Individually, these small-scale
magnetic reconnections are not significant events; not a lot of energy is produced. But the
cumulative effect of maybe trillions of these things might account for the
corona’s million degree temperature. It sure looks like that’s
what’s happening here, but just because something looks
like what you expect to see, doesn’t mean it is. Even if the
campfires really turn out to be nano flares, it doesn’t mean they’re
producing enough energy to account for the corona’s temperature. It’s also
possible that these aren’t nano flares at all, but some other phenomenon
that mimics their appearance. Speaking of mimicking appearances,
there’s also what appears to be a giant tardigrade about 2/3 the
size of Earth jumping around. This is actually a defect in
the EUI sensor. The reason it’s jumping around is because the
original images were a bit shaky. The EUI team corrected this and
stabilized the images. But now that the images are rock solid, the original
defects of the sensor become shaky. Eventually, the EUI team will be able
to further optimize their imaging algorithms and remove the defects
from future images. But for now, we have a giant tardigrade and his
buddies jumping around campfires. In order to find out what these
campfires really are, Solar Orbiter needs to get a lot closer to the Sun,
but getting there will take some time. You see, getting to the Sun requires
getting rid of a lot of orbital energy inherited from Earth. To do
that, Solar Orbiter will make a series of flybys of Venus
- and one flyby of Earth - to dump orbital momentum and
descend closer to the Sun. Eventually, it will reach a closest
approach of about 0.3 AU in October 2022. There, the spacecraft will make
its highest resolution images as well as direct in situ measurements of the
solar wind particles as they pass by. Additional Venus flybys will
send Solar Orbiter to higher and higher inclinations
above the ecliptic plane. That will allow the spacecraft
to obtain the first direct images of the Sun’s north and south polar
regions. The only other spacecraft to fly over the Sun’s poles was
Ulysses, which was launched in 1990. Ulysses used a gravity assist
from Jupiter to change its orbit and overfly the Sun. But it
didn’t carry any cameras. Instead, it made in situ measurements of the
environment surrounding the spacecraft as it flew overhead. After three
orbits, Ulysses was retired in 2009. Solar Orbiter won’t directly overly the
Sun’s poles, because it won’t be able to generate enough change in velocity with
flybys of Venus. But it will be able to image the poles and study how the
Sun’s magnetic field converges there. Solar Orbiter is equipped with
6 remote sensing instruments and 4 in situ instruments. The Extreme Ultraviolet Imager images the Sun’s lower atmosphere
at ultraviolet wavelengths. This alone is the reason why we need
a spacecraft in the first place. The Daniel K. Inouye Solar Telescope is
the largest solar telescope ever built. When commissioned in 2019, it made
the highest-resolution images of the Sun to date, revealing details
as small as 30km (18 miles) across. However, DKIST is underneath Earth’s
atmosphere, which blocks most of the Sun’s ultraviolet radiation. In order
to study the high-energy corona, we need to go to space so we
can see at UV wavelengths. The METIS coronagraph images
the corona by blocking out the Sun. It makes two images simultaneously; one in visible light, shown in
green, and one in ultraviolet light, shown in red. The ultraviolet light is
caused from emission by neutral hydrogen in the corona. The images show streamers
emanating from the Sun’s equator, which is pretty typical of the
Sun during its quiet period. However, METIS captured even
higher resolution images when it closed in to
0.52 AU on June 21st. The Heliospheric Imager - or SoloHI
- images the solar wind by capturing the light scattered by electrons in the
wind. This image is a mosaic from four separate detectors in the imager. The
partial ellipse visible on the right is sunlight reflecting off the dust
particles that are orbiting the Sun. This is called Zodiacal light. The solar
wind outflow is faint by comparison, but the SoloHI team developed
techniques to reveal it. The Polarimetric and
Helioseismic Imager (PHI) measures the magnetic field near the
Sun's surface. It also allows for the investigation of the Sun's interior
via the technique of helioseismology. The PHI Full Disk Telescope shows the
Sun pretty much as it would appear to the naked eye, as long as it was
wearing enough welding glasses. The lack of sunspots really shows how
magnetically quiet the Sun is right now. PHI’s High Resolution Telescope
reveals a magnetogram of the surface. The small structures seen
here are magnetic regions with north and south polarities, some
of which have sizes of a few 1000 km. From this data, magnetic field
lines can be extrapolated into the upper solar atmosphere,
which the EUI telescope images. The same region imaged by the
magnetogram is shown here in visible light, which reveals the
Sun’s photosphere. The granules are the up and down convection cells
of hot, electrically charged plasma. That’s just four of the 10 instruments
aboard Solar Orbiter. Four other instruments are in situ instruments to
measure the magnetic field, sample the solar wind, charged particles, and radio
and plasma waves. These instruments will become very important when Solar
Orbiter gets closer to the Sun. However, Solar Orbiter won't
come anywhere near as close as the Parker Solar Probe. When Parker
makes its closest approach, Parker will come to within 0.05 AU. It will
actually fly through the Sun’s corona! So it's natural to wonder why
they didn't just put a camera on Parker to take even closer images?
Well, it turns out that at 0.05 AU, the radiation environment
is so strong that there's no feasible way to fit a camera capable
of surviving those conditions. However, its WISPR camera looks sideways
to image the solar wind passing by. So the two spacecraft compliment
each other, each making different measurements in different regions.
A while back, I made a video about Parker just before it launched. So,
if you’d like to learn more about the Parker mission, make sure to check
out this video when we’re done here. My thanks as always to my patrons
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and VonKickass. And a special thanks as always to
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