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Under Namibian Skies is a film by Lorenzo Comolli, based on images take by him,
 
Under Namibian Skies is a film by Lorenzo Comolli, based on images take by him,
 
Luigi Fontana, Giosue Ghioldi, and Emmanuele Sordini, with music by Vladimir
 
Luigi Fontana, Giosue Ghioldi, and Emmanuele Sordini, with music by Vladimir
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Return here after you have seen the film in its entirety.
 
Return here after you have seen the film in its entirety.
 +
  
 
== Where were you and what time was it? ==
 
== Where were you and what time was it? ==
  
 
When you viewed the film there was a date and time indicated on the bottom left.
 
When you viewed the film there was a date and time indicated on the bottom left.
These are in "Universal Time" or  "UT", that is, the time on the prime meridian
+
These are in [http://en.wikipedia.org/wiki/Universal_Time "Universal Time" or  "UT"], the time on the prime meridian
 
that is the reference line for geographic longitude on Earth.   
 
that is the reference line for geographic longitude on Earth.   
  
1. Where is Namibia? Identify the continent it is in, above or below the
+
1. Where is [http://en.wikipedia.org/wiki/Namibia Namibia]? Identify the continent it is in, above or below the
 
equator, its latitude in degrees, east or west of the prime meridian, and
 
equator, its latitude in degrees, east or west of the prime meridian, and
 
longitude in hours.
 
longitude in hours.
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2.  When it is 10 PM in Namibia, what time is it where you presently are on
 
2.  When it is 10 PM in Namibia, what time is it where you presently are on
 
Earth?
 
Earth?
 +
  
 
== Sunset ==
 
== Sunset ==
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above you and behind you, that is, on an arc that goes back toward the north.   
 
above you and behind you, that is, on an arc that goes back toward the north.   
  
Short after this, about 40 seconds into the film, you see sunset again.  Oddly
+
Shortly after this, about 40 seconds into the film, you see sunset again.  Oddly
 
now the the Sun is setting more north of those palm trees.  The film identifies
 
now the the Sun is setting more north of those palm trees.  The film identifies
 
the date as August 24, 2011.   
 
the date as August 24, 2011.   
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make a reasoned estimate of what season it was when the first sunset (at
 
make a reasoned estimate of what season it was when the first sunset (at
 
20 seconds) was filmed.  Explain your reasoning!
 
20 seconds) was filmed.  Explain your reasoning!
 +
  
 
== Find the nearest neighboring star and a distant cluster ==
 
== Find the nearest neighboring star and a distant cluster ==
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upward from the horizon.  Notice the bright object about half way toward the
 
upward from the horizon.  Notice the bright object about half way toward the
 
horizon and a little toward the south (right) at this moment.  It is not a star,
 
horizon and a little toward the south (right) at this moment.  It is not a star,
but it's name is Omega Centauri.  You may need Google to find this answer!
+
but its name is Omega Centauri.  You may need Google to find this answer!
  
  
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This is dust in the plane of our solar system, scattering sunlight that we see
 
This is dust in the plane of our solar system, scattering sunlight that we see
 
as a faintly glowing column.  To experience this almost as you would if you were
 
as a faintly glowing column.  To experience this almost as you would if you were
there, freeze the move at this point.  Sit close to the screen so that the wide
+
there, freeze the movie at this point.  Sit close to the screen so that the wide
 
high definition (HD) field seems to surround you.  The movie shows a field that
 
high definition (HD) field seems to surround you.  The movie shows a field that
is about 180 degrees wide and 100 degrees high.
+
is about 180 degrees across and 100 degrees high.
  
 
The "ZODIACAL LIGHT" label coincidentally is also pointing toward a star-like
 
The "ZODIACAL LIGHT" label coincidentally is also pointing toward a star-like
 
object.  It's Saturn.  The bright star above it and slightly south (left) is
 
object.  It's Saturn.  The bright star above it and slightly south (left) is
Spica, Alpha Virginis, the brightest star in the constellation Virgo.  The
+
[http://en.wikipedia.org/wiki/Spica Spica], Alpha Virginis, the brightest star in the constellation Virgo.  The
bright star under the label is Arctaurus, Alpha Bootes, the brightest star in
+
bright star under the label is [http://en.wikipedia.org/wiki/Arcturus Arcturus], Alpha Bootes, the brightest star in
 
Bootes.
 
Bootes.
  
 +
5.  Explain why Saturn appears to be in the Zodiacal Light.
  
5.  Explain why Saturn appears to be in the Zodiacal Light.
 
  
  
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sunset.  The Milky Way would be overhead in the real sky, and even here, seen as
 
sunset.  The Milky Way would be overhead in the real sky, and even here, seen as
 
an image on a flat screen, it is stunning as it spans upward from the southern
 
an image on a flat screen, it is stunning as it spans upward from the southern
horizon on your left (west is nearly in front of you).  The bright star Antares,
+
horizon on your left (west is nearly in front of you).  The bright star [http://en.wikipedia.org/wiki/Antares Antares],
 
Alpha Scorpi, is below the bulge and left of the label.   
 
Alpha Scorpi, is below the bulge and left of the label.   
  
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it is nearly parallel to the horizon, the the bulge is just above one of the
 
it is nearly parallel to the horizon, the the bulge is just above one of the
 
palm trees.  The teapot is almost upside down, above the tall tree on the left.
 
palm trees.  The teapot is almost upside down, above the tall tree on the left.
 +
 +
 +
== Locate the satellite galaxies to the Milky Way ==
  
 
Nearly fours hours later, at UT 03:45, Jupiter is visible as  the Earth's
 
Nearly fours hours later, at UT 03:45, Jupiter is visible as  the Earth's
 
rotation carries us around to bring it into view at the upper right.  Those are
 
rotation carries us around to bring it into view at the upper right.  Those are
the Pleiades, a cluster of stars about 125 light years from us , just above and
+
the [http://en.wikipedia.org/wiki/Pleiades Pleiades], a cluster of stars about 400 light years from us , just above and
right of Jupiter. The Pleiades are in Taurus, and most of the constellation is
+
right of Jupiter. The Pleiades are in [http://en.wikipedia.org/wiki/Taurus_%28constellation%29 Taurus], and most of the constellation is
off the image.  Jupiter is in  Aries.  The bright star above Jupiter close to
+
off the image.  Jupiter is in  [http://en.wikipedia.org/wiki/Aries_%28constellation%29 Aries].  The bright star above Jupiter close to
the top of the frame is Menkar, Alpha Ceti.
+
the top of the frame is [http://en.wikipedia.org/wiki/Cetus Menkar, Alpha Ceti].
 
 
== Locate the satellite galaxies to the Milky Way ==
 
  
 
7. What is that hazy patch of light, near the left side of the image at the top
 
7. What is that hazy patch of light, near the left side of the image at the top
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patch?
 
patch?
  
 +
 +
 +
== Find a familiar star pattern ==
  
 
As the film continues it takes you to sunset of the following night, now with a
 
As the film continues it takes you to sunset of the following night, now with a
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hemisphere.   
 
hemisphere.   
  
== Find a familiar star pattern ==
 
  
 +
8.  What are the three stars of the [http://en.wikipedia.org/wiki/Summer_triangle Summer Triangle], and what constellations are
 +
they in?
  
8.  What are the three stars of the Summer Triangle, and what constellations are
 
they in? 
 
  
 
== Identify satellites in geosynchronous orbit around Earth ==
 
== Identify satellites in geosynchronous orbit around Earth ==
  
Just afterward we see a geostationary satellite appear as it glints sunlight. Satellites like this one at a distance from Earth such that they complete an orbit around it in the same time, on average, that it takes Earth to rotate once with respect to the stars.  That is, they hover over the same spot on Earth.  
+
Just afterward we see a [http://en.wikipedia.org/wiki/Geosynchronous_satellite geosynchronous or "geostationary"] satellite appear as it glints sunlight. Satellites like this one at a distance from Earth such that they complete an orbit around it in the same time, on average, that it takes Earth to rotate once with respect to the stars.  That is, they hover over the same spot on Earth.  
  
  
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+
== Use an upside down Orion to find your way ==
== Use an upside down Orion to find your way ==
 
  
  
At 02:24 into the film, Jupiter is seen above the northern horizon and Orion has
+
At 02:24 into the film, Jupiter is seen above the northern horizon and [http://en.wikipedia.org/wiki/Orion_%28constellation%29 Orion] has
 
risen int he east.  It's upside down from how we would see it in the northern
 
risen int he east.  It's upside down from how we would see it in the northern
 
hemisphere (or more correctly, we are upside down compared to the familiar view
 
hemisphere (or more correctly, we are upside down compared to the familiar view
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On your left, which would be toward the west because in this view you're looking
 
On your left, which would be toward the west because in this view you're looking
north with east on your right, the Great Square of Pegasus is bove the horizon,
+
north with east on your right, the Great Square of [http://en.wikipedia.org/wiki/Pegasus_%28constellation%29 Pegasus] is bove the horizon,
 
almost directly over the second red light from the edge.  Look carefully and you
 
almost directly over the second red light from the edge.  Look carefully and you
may be able to pick out the Andromeda Galaxy to the right of that light and 20
+
may be able to pick out the [http://en.wikipedia.org/wiki/Andromeda_Galaxy Andromeda Galaxy] to the right of that light and 20
 
degrees above the horizon.  In the northern hemisphere this galaxy is just
 
degrees above the horizon.  In the northern hemisphere this galaxy is just
 
visible to the unaided eye when it is overhead in the fall.   
 
visible to the unaided eye when it is overhead in the fall.   
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At 02:33 the film shows us the sky seen looking southeast.  The south celestial
 
At 02:33 the film shows us the sky seen looking southeast.  The south celestial
 
pole is highlighted at 18:14 UT, just after sunset, and by 22:35 UT we see the
 
pole is highlighted at 18:14 UT, just after sunset, and by 22:35 UT we see the
Large and Small Magellanic Clouds (LMC and SMC) rising.
+
Large and Small [http://en.wikipedia.org/wiki/Magellanic_clouds Magellanic Clouds] (LMC and SMC) rising.
  
 
As the night goes by and morning twilight arrives around 04 UT, both of
 
As the night goes by and morning twilight arrives around 04 UT, both of
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In the frames that follow you see the sky setting in the west, and then the view
 
In the frames that follow you see the sky setting in the west, and then the view
 
pans around toward the south again to see the Magellanic Clouds high over the
 
pans around toward the south again to see the Magellanic Clouds high over the
pole before sunrise.  The bright stars Achernar and Canopus are highlighted at
+
pole before sunrise.  The bright stars [http://en.wikipedia.org/wiki/Achernar Achernar] and [http://en.wikipedia.org/wiki/Canopus Canopus] are highlighted at
 
04:09 into the film, seen at 02:24 UT in Namibia that night.  These are two fo
 
04:09 into the film, seen at 02:24 UT in Namibia that night.  These are two fo
 
the brightest southern sky stars, and Canopus is Alpha Carinae, the brightest
 
the brightest southern sky stars, and Canopus is Alpha Carinae, the brightest
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the right time of year.
 
the right time of year.
  
 +
 +
== Watch the Moon set ==
  
 
Remember that on the first night of the film we had a faint crescent Moon just
 
Remember that on the first night of the film we had a faint crescent Moon just
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nights, and the camera lens has changed to show less of the sky, but more
 
nights, and the camera lens has changed to show less of the sky, but more
 
detail.
 
detail.
 
== Watch the Moon set ==
 
  
  
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15.  What direction is it to moonset now?  Is it the same as it was when it was
 
15.  What direction is it to moonset now?  Is it the same as it was when it was
 
a crescent?  Explain.
 
a crescent?  Explain.
 +
  
 
== Unusual sightings ==
 
== Unusual sightings ==
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As the film continues to its conclusion, you will see again things you have noticed already, but
 
As the film continues to its conclusion, you will see again things you have noticed already, but
 
now they will be more familiar.  There are new things to look at too.  Around
 
now they will be more familiar.  There are new things to look at too.  Around
06:33, at 2011-08-25 20:38 UT, the two bright stars Alpha and Beta Centauri come
+
06:33, at 2011-08-25 20:38 UT, the two bright stars [http://en.wikipedia.org/wiki/Alpha_Centauri Alpha] and [http://en.wikipedia.org/wiki/Beta_Centauri Beta] [http://en.wikipedia.org/wiki/Centaurus Centauri] come
 
into our view looking southwest.  Moments later, the film briefly hightlights
 
into our view looking southwest.  Moments later, the film briefly hightlights
 
the Southern Cross.  See if you can find this moment.   
 
the Southern Cross.  See if you can find this moment.   
  
  
16. What do you see in the Milky Way, at the edge of the Southern Cross?
+
16. What do you see in the Milky Way, at the edge of the [http://en.wikipedia.org/wiki/Southern_cross Southern Cross]?
  
  
 
Beginning at about 11 minutes into the film, the camera's fisheye view shows the entire
 
Beginning at about 11 minutes into the film, the camera's fisheye view shows the entire
sky. At first you see the zodiacal light coming up from the western horizon,
+
sky. At first you see the [http://en.wikipedia.org/wiki/Zodiacal_light zodiacal light] coming up from the western horizon,
 
dimming as it gets higher and farther from the Sun.  Then, starting at about
 
dimming as it gets higher and farther from the Sun.  Then, starting at about
 
11:10 into the film ad at 2011-08-30 18:06 UT you'll see that this light
 
11:10 into the film ad at 2011-08-30 18:06 UT you'll see that this light
 
continues across the sky, through the Milky Way and is visible quite distinctly.
 
continues across the sky, through the Milky Way and is visible quite distinctly.
In this geometry, the light is called "Gegenshein", meaning "counter" shine,
+
In this geometry, the light is called [http://en.wikipedia.org/wiki/Gegenschein "Gegenshein"], meaning "counter" shine,
 
opposite in direction to the Sun.  
 
opposite in direction to the Sun.  
  
 
17. At this time of year, when the Sun is under
 
17. At this time of year, when the Sun is under
our feet in Nambian, where does the Gegenshein appear?  Look at the frames
+
our feet in Nambia, where does the Gegenshein appear?  Look at the frames
beginning at 013:25.
+
beginning at 13:25.

Latest revision as of 19:29, 5 October 2013

Under Namibian Skies is a film by Lorenzo Comolli, based on images take by him, Luigi Fontana, Giosue Ghioldi, and Emmanuele Sordini, with music by Vladimir Sterzer. It is Copyright 2011 and the version we offer in our immersive video room for this class is in high definition (HD).


View the film

As you will see when you view it, the film is based on time lapse images of the sky, and it compresses them into an experience of an entire night in a brief 15 minutes. To do this, they have selected image sequences looking in different directions over a few nights in late August and early September, 2011. It starts with a view to the west, then follows with ones to the north, then the east and finally the south. Begin this lab activity by watching it it all the way through now, full screen and in the darkened visualization room if you are in the on-campus lab. The film is also available on YouTube:

Under Namibian Skies

After that, we will have you consider some of the ideas it raises while you review parts of it frame by frame.

Return here after you have seen the film in its entirety.


Where were you and what time was it?

When you viewed the film there was a date and time indicated on the bottom left. These are in "Universal Time" or "UT", the time on the prime meridian that is the reference line for geographic longitude on Earth.

1. Where is Namibia? Identify the continent it is in, above or below the equator, its latitude in degrees, east or west of the prime meridian, and longitude in hours.

2. When it is 10 PM in Namibia, what time is it where you presently are on Earth?


Sunset

About 20 seconds into the film, the Sun sets in the west (notice the palm trees), and soon after the cresent Moon appears. Notice that the track of the Moon (and a hint of of the earlier track of the Sun) suggests it is coming from above you and behind you, that is, on an arc that goes back toward the north.

Shortly after this, about 40 seconds into the film, you see sunset again. Oddly now the the Sun is setting more north of those palm trees. The film identifies the date as August 24, 2011.


3. Based on the images in the film, make a reasoned estimate of what season it was when the first sunset (at 20 seconds) was filmed. Explain your reasoning!


Find the nearest neighboring star and a distant cluster

Later that night the camera has panned more toward the southwest, and at 1 minute into the film you see Alpha Centauri, the Sun's close celestial neighbor, with the Milky way as a backdrop. Just below Alpha Centauri is Beta Centauri, the second brightest star in Centaurus. The Milky Way, our own galaxy, streaks upward from the horizon. Notice the bright object about half way toward the horizon and a little toward the south (right) at this moment. It is not a star, but its name is Omega Centauri. You may need Google to find this answer!


4. What is Omega Centauri, where is it with respect to our galaxy the Milky Way, and how much farther is it from us than the closest star, Alpha Centauri? While you answer these questions, ponder this view, with both Alpha and Omega apparently separated by only 16 degrees in this beautiful dark sky.


What is zodiacal light?

Moments later in the film it is the following night (now August 25, 2011) and soon after sunset. The annotation in the film points out the zodiacal light. This is dust in the plane of our solar system, scattering sunlight that we see as a faintly glowing column. To experience this almost as you would if you were there, freeze the movie at this point. Sit close to the screen so that the wide high definition (HD) field seems to surround you. The movie shows a field that is about 180 degrees across and 100 degrees high.

The "ZODIACAL LIGHT" label coincidentally is also pointing toward a star-like object. It's Saturn. The bright star above it and slightly south (left) is Spica, Alpha Virginis, the brightest star in the constellation Virgo. The bright star under the label is Arcturus, Alpha Bootes, the brightest star in Bootes.

5. Explain why Saturn appears to be in the Zodiacal Light.


See the center of our galaxy

At 1:15 into the film a label "Milky Way Bulge" appears. Pause at this point and consider the view you have now. The time is 20:15 UT, a few hours after sunset. The Milky Way would be overhead in the real sky, and even here, seen as an image on a flat screen, it is stunning as it spans upward from the southern horizon on your left (west is nearly in front of you). The bright star Antares, Alpha Scorpi, is below the bulge and left of the label.

6. What constellation is above the bulge, near the top of he frame? Hint: on a sky map it is east of Scorpius and it looks like a teapot. In this case, the teapot's spigot is down and its handle is up.

Let the movie run and the Milky Way will drop toward the horizon. At UT 00:00 it is nearly parallel to the horizon, the the bulge is just above one of the palm trees. The teapot is almost upside down, above the tall tree on the left.


Locate the satellite galaxies to the Milky Way

Nearly fours hours later, at UT 03:45, Jupiter is visible as the Earth's rotation carries us around to bring it into view at the upper right. Those are the Pleiades, a cluster of stars about 400 light years from us , just above and right of Jupiter. The Pleiades are in Taurus, and most of the constellation is off the image. Jupiter is in Aries. The bright star above Jupiter close to the top of the frame is Menkar, Alpha Ceti.

7. What is that hazy patch of light, near the left side of the image at the top of the frame? The south celestial pole is just to the edge of this frame, to the left close to the top. Use Google to find its distance in light years. If Jupiter was about 30 light minutes from us at that time, how much farther is it to this hazy patch?


Find a familiar star pattern

As the film continues it takes you to sunset of the following night, now with a view centered toward the north, with east to your left. The lights of the nearby town on the horizon at your right make a convenient reference point. At 01:56 the film labels the three bright stars of the summer triangle, a configuration of stars that is familiar to sky watchers in the northern hemisphere.


8. What are the three stars of the Summer Triangle, and what constellations are they in?


Identify satellites in geosynchronous orbit around Earth

Just afterward we see a geosynchronous or "geostationary" satellite appear as it glints sunlight. Satellites like this one at a distance from Earth such that they complete an orbit around it in the same time, on average, that it takes Earth to rotate once with respect to the stars. That is, they hover over the same spot on Earth.


9. In addition to its sudden appearance and then disappearance, what is it about the geostationary satellite that tells us it is not a star? Explain.

Later in the film, at about 07:15, the camera is looking toward the roll-off-roof telescope shelter, and the film highlights the line over which geostationary satellites may appear.


10. How many geostationary satellites did you pick out? Hint: It's more than one!


Use an upside down Orion to find your way

At 02:24 into the film, Jupiter is seen above the northern horizon and Orion has risen int he east. It's upside down from how we would see it in the northern hemisphere (or more correctly, we are upside down compared to the familiar view when we are in Namibia). Locate Orion.


11. What is that bright reddish star on the lower right corner of the upside down constellation?


On your left, which would be toward the west because in this view you're looking north with east on your right, the Great Square of Pegasus is bove the horizon, almost directly over the second red light from the edge. Look carefully and you may be able to pick out the Andromeda Galaxy to the right of that light and 20 degrees above the horizon. In the northern hemisphere this galaxy is just visible to the unaided eye when it is overhead in the fall.


At 02:33 the film shows us the sky seen looking southeast. The south celestial pole is highlighted at 18:14 UT, just after sunset, and by 22:35 UT we see the Large and Small Magellanic Clouds (LMC and SMC) rising.

As the night goes by and morning twilight arrives around 04 UT, both of theses small neighboring galaxies are above the south celestial pole. In the frames that follow sunrise that morning, the movie shows a "star trail" view that illustrates the track of stars around the south celestial pole. Draw an imaginary line from the pole through the LMC and toward the upper left.


12. What familiar constellation is on that line, close to the upper left corner of the image? It might be easiest to pick out in the frame at 03:09, before the star trail sequence.


In the frames that follow you see the sky setting in the west, and then the view pans around toward the south again to see the Magellanic Clouds high over the pole before sunrise. The bright stars Achernar and Canopus are highlighted at 04:09 into the film, seen at 02:24 UT in Namibia that night. These are two fo the brightest southern sky stars, and Canopus is Alpha Carinae, the brightest star in Carina while Achernar is the brightest star in Eridanus. Canopus has a declination of about -52.6 degrees, that is, it is about 52.6 degrees below the celestial equator.


13. Identify a city in the United States from which Canopus would be visible. The best answer would be one where Canopus could probably be sighted easily at the right time of year.


Watch the Moon set

Remember that on the first night of the film we had a faint crescent Moon just visible above the horizon at sunset. As the film progresses it spans several nights, and the camera lens has changed to show less of the sky, but more detail.


14. On 2011-08-31, what time did the Moon set (UT)? Use the palm trees as a reference to get a sense of direction. Was the moonset south of, north of , or exactly the same as the sunset direction?

Skip forward and watch the view from inside the observatory in the section that follows. By 2011-09-02 the gibbous Moon sets just before sunrise.

15. What direction is it to moonset now? Is it the same as it was when it was a crescent? Explain.


Unusual sightings

As the film continues to its conclusion, you will see again things you have noticed already, but now they will be more familiar. There are new things to look at too. Around 06:33, at 2011-08-25 20:38 UT, the two bright stars Alpha and Beta Centauri come into our view looking southwest. Moments later, the film briefly hightlights the Southern Cross. See if you can find this moment.


16. What do you see in the Milky Way, at the edge of the Southern Cross?


Beginning at about 11 minutes into the film, the camera's fisheye view shows the entire sky. At first you see the zodiacal light coming up from the western horizon, dimming as it gets higher and farther from the Sun. Then, starting at about 11:10 into the film ad at 2011-08-30 18:06 UT you'll see that this light continues across the sky, through the Milky Way and is visible quite distinctly. In this geometry, the light is called "Gegenshein", meaning "counter" shine, opposite in direction to the Sun.

17. At this time of year, when the Sun is under our feet in Nambia, where does the Gegenshein appear? Look at the frames beginning at 13:25.