APOD: The Windmill and the Star Trails (2020 Apr 17)

[APOD Robot]

The Windmill and the Star Trails

Explanation: Stars can't turn these old wooden arms, but it does look like they might in this scene from a rotating planet. The well-composed night skyscape was recorded from Garafia, a municipality on the island of La Palma, Canary Islands, planet Earth. The center of the once working windmill, retired since 1953, is lined-up with the north celestial pole, the planet's rotation axis projected on to the northern sky. From a camera fixed to a tripod, the star trails are a reflection of the planet's rotation traced in a digital composite of 39 sequential exposures each 25 seconds long. Brought out by highlighting the final exposure in the sequence, the stars themselves appear at the ends of their short concentric arcs. A faint band of winter's Milky Way and even a diffuse glow from our neighboring Andromeda Galaxy also shine in the night.

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[Ann]

The Windmill and the Star Trails Antonio Gonzalez.png

Today's APOD is a very nice picture where you can actually identify some of the deep-sky objects!

Just above the orange cloud bank you can see a cluster, and I was about to ask the same question as I asked last time, when the APOD was Star Trails Over Ragusa, "What cluster is that?". Joe Stieber helped me out by identifying it as the Alpha Persei Moving Cluster, seen here in a photo by Naoyuki Kurita.

Move to the upper left from the Alpha Persei Moving Cluster, and you'll come to two blurry but bright and obvious white splotches, which are very close together. They are, of course, the Double Cluster in Perseus, NGC 869 and NGC 884.

Heart and Soul Nebulas, the Double Cluster and most of Cassiopeia. Photo: Dimitrios Tsortanidis.

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To the left of the Double Cluster in the APOD are two extended pink nebulas. They are the Heart and Soul Nebulas. I like Dimitrios Tsortanidis' picture so much that I want to show you his picture and not just a link to it. The Heart Nebula is the larger nebula and the Soul Nebula is the smaller one. You can also see how close the Double Cluster is (at least in the sky) to the Heart and Soul Nebulas.

The next extended pink splotch, visible if you move upwards and just a little bit to the left, is NGC 7822, seen here in a picture by Davide De Martin and ESA/ESO/NASA.

The 'W' of Cassiopeia, the Double Cluster and the Andromeda Galaxy. Photo: Bob King.

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In the picture by Bob King at left, you can see the "W" of Cassiopeia (which is really hard to spot in the APOD), the Double Cluster and the Andromeda Galaxy. Note in Bob King's picture an orange-tinted star just barely peeking out behind the line of trees, below Andromeda. That star is Beta Andromedae, and it stands out quite well in the APOD, where it looks bright and orange.

IC 1396 by Mario Richter.png

IC 1396 with red supergiant Mu Cephei at the edge,
Photo: Mario Richter.

The pink splotch at top in the APOD is IC 1396, easily recognized by the fact that bright orange supergiant star Mu Cephei is located at the edge of this nebula.

Ann

[Guest]

Stars can't turn these old wooden arms

But arms are already turning once a day, and the camera is turning with them! This is what causes the star images to form trails.

Lovely idea for a star trail image.

[orin stepanek]

I think this picture is special; windmill kind of reminds me of "Old Rugged Cross!"

[neufer]

Stars can't turn these old wooden arms

But arms are already turning once a day, and the camera is turning with them! This is what causes the star images to form trails.

If the axis of windmill rotation was pointed directly at the North Star: it would be turning once a day.

However...just as with a Foucault pendulum one must take into account the cosine
of the angle between the Earth's axis and the axis of symmetry of the object in question.

[MarkBour]

Click to play embedded YouTube video.

... and the world is like an apple whirling silently in space,
like the circles that you find in the windmills of your mind.

[Cousin Ricky]

Click to play embedded YouTube video.

... and the world is like an apple whirling silently in space,
like the circles that you find in the windmills of your mind.

My KJ couldn’t find a karaoke version of Noel Harrison’s version, but he did have the Sting cover.

Click to play embedded YouTube video.

Click to play embedded YouTube video.

...Le voyage autour du monde d’un tournesol dans sa fleur
Tu fais tourner de ton nom tous les moulins de mon coeur

[neufer]

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Cyrano de Bergerac (1950)

Antoine Comte de Guiche: As for you sir, have you read "Don Quixote"?

Cyrano de Bergerac: I have, and found myself the hero.

Antoine Comte de Guiche: Be so good as to read once more the chapter of the windmills...

Cyrano de Bergerac: Chapter thirteen!

Antoine Comte de Guiche: Windmills, remember, if you fight with them... may swing round their huge arms and cast you down into the mire!

Cyrano de Bergerac: Or up, among the stars!

Click to play embedded YouTube video.

[cheersforann]

Thank goodness for Ann who makes sense of so many APODS which would otherwise be puzzles and worded mysteries.

[Ann]

Thank goodness for Ann who makes sense of so many APODS which would otherwise be puzzles and worded mysteries.

Wow, that's amazing. I'm humbled. Thank you.

Ann

[neufer]

Stars in Motion

The ISS on 23 May 2010, as seen from STS-132

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May 17, 2012

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<<The International Space Station (ISS) is constantly in motion. The football pitch-sized object cruises at about 29,000 kilometers per hour—so fast that it orbits Earth every 90 minutes.

For astronaut photographers on board, that motion has consequences. For one, it makes it challenging to take photos. Even with digital cameras that take pictures within 1/1000th of a second, the Space Station moves so quickly that images can easily lose focus or become distorted.

However, the same motion makes it possible to shoot spectacular photos like the one above. The image is compiled from a series of photographs taken by NASA astronaut Don Pettit while he was onboard the ISS in April 2012. This composite was made from more than 72 individual long-exposure photographs taken over several minutes as the ISS traveled over the Caribbean Sea, across South America, and over the South Atlantic Ocean.

As Pettit explained in a blog post, long-exposure pictures from the Station show star trails as circular arcs, with the center of rotation being the poles of the station. Stars close to the center of rotation make the tight circles near the middle of the image, while stars farther from it make the larger arcs visible along the edges.

“My star trail images are made by taking a time exposure of about 10 to 15 minutes,” Pettit wrote. “However, with modern digital cameras, 30 seconds is about the longest exposure possible, due to electronic detector noise effectively snowing out the image. To achieve the longer exposures, I do what many amateur astronomers do. I take multiple 30-second exposures, then stack them using imaging software, thus producing the longer exposure.”

The image includes many natural and artificial lights that astronauts see while passing over the night side of Earth. On the ground, stationary features like cities appear as pale yellow-white streaks. The thinner, dotted lines with orange hues are likely caused by small fires burning in South America.

Looking toward the horizon, thunderstorms dot the landscape. Many of the compiled frames captured bright white lightning flashes. Above the horizon, a faint green-yellow phenomenon called airglow hugs the upper atmosphere. Look carefully at the large version of this image for at least one streak of light that is not aligned with all the others. That is satellite.>>