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Astronomy Picture of the Day |
APOD: 2025 February 4 – Anticrepuscular Rays: A Rainbow Fan over Spain
Explanation:
Yes, but can your rainbow do this?
Late in the day, the
Sun set as usual toward the west.
However, on this day, the more interesting display was
180 degrees around -- toward the east.
There, not only was a
rainbow visible,
but an impressive display of
anticrepuscular rays
from the rainbow's center.
In the featured image from
Lekeitio in northern
Spain,
the Sun is behind the camera.
The
rainbow
resulted from sunlight reflecting back from falling rain.
Anticrepuscular rays result from sunlight, blocked by some clouds,
going all the way
around the sky, overhead,
and appearing to converge on the opposite horizon -- an optical illusion.
Rainbows by themselves can be exciting to see, and
anticrepuscular rays a
rare treat, but capturing them both together is even more unusual --
and can look both serene and surreal.
APOD: 2024 July 19 - Anticrepuscular Rays at the Planet Festival
Explanation:
For some,
these subtle bands of light and shadow stretched across the sky as the
Sun set on July 11.
Known as
anticrepuscular rays,
the bands are formed as a large
cloud bank near the western horizon cast
long shadows
through the atmosphere at sunset.
Due to the camera's perspective, the bands of light and shadow
seem to converge toward the eastern (opposite) horizon at a point seen
just above a 14th century
hilltop castle
in Brno, Czech Republic.
In the foreground,
denizens
of planet Earth are enjoying the region's annual
Planet Festival
in the park below the Brno Observatory and Planetarium.
And while crepuscular and anticrepuscular rays are a relatively
common atmospheric phenomenon, this festival's 10 meter diameter
inflatable spheres representing
bodies of the Solar System
are less often seen
on planet Earth.
APOD: 2020 March 18 - Anticrepuscular Rays over Florida
Explanation:
What's happening behind those clouds?
Although the scene may appear somehow
supernatural,
nothing more unusual is occurring than a
Sun setting on the other side of the sky.
Pictured here are
anticrepuscular rays.
To understand them, start by picturing common
crepuscular rays that are seen any time that
sunlight pours though scattered clouds.
Now although sunlight indeed travels along
straight lines, the projections of these lines onto the
spherical sky are
great circles.
Therefore, the
crepuscular rays from a
setting (or rising) sun
will appear to
re-converge on the other side of the sky.
At the anti-solar point 180 degrees around from the
Sun, they are referred to as
anticrepuscular rays.
Featured here is a particularly striking display of
anticrepuscular rays photographed in 2016 over
Dry Tortugas National Park
in Florida,
USA.
APOD: 2019 June 24 - Anticrepuscular Rays Converge Opposite the Sun
Explanation:
Is there ever anything interesting to see in the direction opposite the Sun?
Sometimes there is.
Notable items include
your own shadow,
a shadow of the Moon during a total solar eclipse,
a full moon --
in eclipse if the alignment's good enough,
a full earth,
planets
at
opposition,
glints from
planets,
the gegenschein from interplanetary dust,
the center of a rainbow,
hall-of-mountain fogbows,
an airplane glory,
and something
yet again different if your timing, clouds and Sun position are
just right.
This different effect starts with clouds near the
Sun
that are causing common
crepuscular rays to stream through.
In the featured rare image taken from an airplane in mid-April,
these beams were caught converging
180 degrees around,
on the opposite side of the sky from the Sun, where they are called
anticrepuscular rays.
Therefore, it may look like
something
bright is shining at the
antisolar point
near the image center, but actually it is
reverse-shining because, from your direction, light is streaming in, not out.
APOD: 2016 June 27 - Anticrepuscular Rays over Colorado II
Explanation:
What's happening over the horizon?
Although the scene may appear somehow
supernatural,
nothing more unusual is occurring than a
setting Sun and some well placed clouds.
Pictured above are
anticrepuscular rays.
To understand them, start by picturing common
crepuscular rays that are seen any time that
sunlight pours though scattered clouds.
Now although sunlight indeed travels along
straight lines, the projections of these lines onto the
spherical sky are
great circles.
Therefore, the
crepuscular rays from a
setting (or rising) sun
will appear to
re-converge on the
other side of the sky.
At the anti-solar point 180 degrees around from the
Sun, they are referred to as
anticrepuscular rays.
Featured here is a particularly striking display of
anticrepuscular rays photographed earlier this month in
Westminster,
Colorado,
USA.
APOD: 2015 July 28 - Rainbows and Rays over Bryce Canyon
Explanation:
What's happening over Bryce Canyon?
Two different optical effects that were captured in
one image taken earlier this month.
Both effects needed to have the Sun situated directly behind the photographer.
The nearest apparition was the common
rainbow,
created by sunlight streaming from the setting sun over the head of the photographer,
and scattering from raindrops in front of the canyon.
If you look closely, even a
second rainbow appears above the first.
More rare, and perhaps more striking, are the rays of light that emanate out from the horizon above the canyon.
These are known as anticrepuscular rays
and result from sunlight streaming though breaks in the clouds, around the sky, and
converging at the point 180 degrees around from the Sun.
Geometrically, this
antisolar point
must coincide with the exact center of the rainbows.
Located in Utah, USA,
Bryce Canyon itself
contains a
picturesque array of ancient
sedimentary rock spires known as
hoodoos.
APOD: 2012 February 21 - Anticrepuscular Rays Over Wyoming
Explanation:
What's happening over the horizon?
Although the scene may appear somehow
supernatural,
nothing more unusual is occurring than a
setting Sun and some well placed clouds.
Pictured above are
anticrepuscular rays.
To understand them, start by picturing common
crepuscular rays that are seen any time that
sunlight pours though scattered clouds.
Now although sunlight indeed travels along
straight lines, the projections of these lines onto the
spherical sky are
great circles.
Therefore, the
crepuscular rays from a
setting (or rising) sun
will appear to
re-converge on the other side of the sky.
At the anti-solar point 180 degrees around from the
Sun, they are referred to as
anticrepuscular rays.
Pictured above is a particularly striking set of
anticrepuscular rays photographed last month near
Cheyenne,
Wyoming,
USA.
APOD: 2010 November 28 - Anticrepuscular Rays Over Colorado
Explanation:
What's happening over the horizon?
Although the scene may appear somehow
supernatural,
nothing more unusual is occurring than a
setting Sun and some well placed clouds.
Pictured above are
anticrepuscular rays.
To understand them, start by picturing common
crepuscular rays that are seen any time that
sunlight pours though scattered clouds.
Now although sunlight indeed travels along
straight lines, the projections of these lines onto the
spherical sky are
great circles.
Therefore, the
crepuscular rays from a
setting (or rising) sun
will appear to re-converge on the other side of the sky.
At the anti-solar point 180 degrees around from the
Sun, they are referred to as
anticrepuscular rays.
Pictured above is a particularly striking set of
anticrepuscular rays photographed in 2001
from a moving car just outside of Boulder,
Colorado,
USA.
APOD: 2010 August 11 - Crepuscular Rays Over Lake Michigan
Explanation:
What could cause such rays of dark?
Dark sky rays were caught in spectacular fashion earlier last month from
Pentwater,
Michigan,
USA, looking west over
Lake Michigan.
The cause is something surprisingly familiar:
shadows.
Clouds near the horizon can
block sunlight from reflecting off air, making columns outward from the
Sun appear
unusually dark.
Cloud shadows can be thought
of as the complement of the more commonly highlighted
crepuscular rays, also visible above, where
sunlight pours though cloud holes.
Sometimes, on the opposite side of the sky,
anticrepuscular rays
can also be seen.
APOD: 2009 February 17 - Unusual Red Glow Over Minnesota
Explanation:
What in heaven's blazes is that?
When landing in
Minneapolis,
Minnesota,
USA in 2002, just before his flight ascended above cloud level in the early evening,
passenger Tyler Blessing saw and photographed "huge curved sheets of
glowing light extending from cloud to ground."
The glow appeared unlike other unusual lights more typically seen, including
crepuscular rays,
anticrepuscular rays and
the
glory.
A leading possibility, mentioned initially by the photographer, is that the light sheets are setting sunlight scattered off of
falling
rain.
Alternatively, the phenomenon could just be a peculiar
window reflection.
APOD readers, who have previously shown an impressive ability to pool their collective intelligence to create a better understanding of
photographed
sky
anomalies, are invited to
discuss this online.
It might help to know that
EXIF data indicates that the image was captured on 2002 September 23 at about 8:07 pm in the evening (local time), and that the camera was reported to be pointing north of west at that time.
The oval on the ground, visible in the lower right of the above image, is
Canterbury Downs race track.
APOD: 2008 November 16 - Anticrepuscular Rays Over Colorado
Explanation:
What's happening over the horizon?
Although the scene may appear somehow
supernatural,
nothing more unusual is occurring than a
setting Sun and some well placed clouds.
Pictured above are
anticrepuscular rays.
To understand them, start by picturing common
crepuscular rays that are seen any time that sunlight pours though scattered clouds.
Now although sunlight indeed travels along
straight lines, the projections of these lines onto the
spherical sky are
great circles.
Therefore, the
crepuscular rays from a
setting (or rising) sun
will appear to re-converge on the other side of the sky.
At the anti-solar point 180 degrees around from the
Sun, they are referred to as
anticrepuscular rays.
Pictured above is a particularly striking set of
anticrepuscular rays photographed in 2001
from a moving car just outside of Boulder,
Colorado,
USA.
APOD: 2006 September 17 - Anticrepuscular Rays Over Florida
Explanation:
What's happening over the horizon?
Although the scene may appear somehow
supernatural,
nothing more unusual is occurring than a
setting Sun and some well placed clouds.
Strangely, the actual sunset was occurring in the opposite direction from where the camera was pointing.
Pictured above are
anticrepuscular rays.
To understand them, start by picturing common
crepuscular rays that are seen any time that sunlight pours though scattered clouds.
Now although sunlight indeed travels along
straight lines, the projections of these lines onto the
spherical sky are
great circles.
Therefore, the
crepuscular rays from a
setting (or rising) sun
will appear to re-converge on the other side of the sky.
At the anti-solar point 180 degrees around from the
Sun, they are referred to as
anticrepuscular rays.
While enjoying the sunset after visiting NASA's
Kennedy Space Center in
Florida,
the photographer chanced to find that an even
more spectacular sight was occurring in the other direction just over the
Atlantic Ocean -- a particularly vivid set of
anticrepuscular rays.
APOD: 2005 August 31 - Crepuscular Rays Over Utah
Explanation:
What could cause such rays of dark?
Dark sky rays were caught in spectacular fashion earlier this month above
Utah,
USA.
The cause is something surprisingly familiar:
shadows.
Clouds near the horizon can block sunlight from
reflecting off air, making columns outward from the
Sun appear
unusually dark.
Cloud shadows can be thought
of as the complement of the more commonly highlighted
crepuscular rays, also visible above, where sunlight pours
though cloud holes.
Sometimes, on the opposite side of the sky,
anticrepuscular rays
can also be seen.
APOD: 2003 February 26 - Anticrepuscular Rays Over Horseshoe Canyon
Explanation:
What's happening over the horizon?
Although the scene may appear somehow
supernatural,
nothing more unusual is occurring than a
setting Sun and some well placed clouds.
Pictured above are
anticrepuscular rays.
To understand them, start by picturing common
crepuscular rays that are seen any time that sunlight pours though scattered clouds.
Now although sunlight indeed travels along
straight lines, the projections of these lines onto the
spherical sky are
great circles.
Therefore, the
crepuscular rays from a
setting (or rising) sun
will appear to re-converge on the other side of the sky.
At the anti-solar point 180 degrees around from the
Sun, they are referred to as
anticrepuscular rays.
While enjoying the sunset after dinner near
Horseshoe Canyon in Utah, the photographer chanced to find that an even
more spectacular sight was occurring in the other direction
just over the canyon -- a particularly vivid set of
anticrepuscular rays.
APOD: 2001 October 30 - Anticrepuscular Rays Over Colorado
Explanation:
What's happening over the horizon?
Although the scene may appear somehow
supernatural,
nothing more unusual is occurring than a
setting Sun and some well placed clouds.
Pictured above are
anticrepuscular rays.
To understand them, start by picturing common
crepuscular rays that are seen any time that sunlight pours though scattered clouds.
Now although sunlight indeed travels along
straight lines, the projections of these lines onto the
spherical sky are
great circles.
Therefore, the
crepuscular rays from a
setting (or rising) sun
will appear to re-converge on the other side of the sky.
At the anti-solar point 180 degrees around from the
Sun, they are referred to as
anticrepuscular rays.
Pictured above is a particularly striking set of
anticrepuscular rays photographed earlier this month
from a moving car just outside of Boulder,
Colorado,
USA.