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kottke.org posts about Milky Way

The Best Photos of the Milky Way for 2023

the Milky Way shines brilliantly at night above the mountains and a layer of clouds

a composite view of the Milky Way combining how it looks in the night sky during the winter and summer

the Milky Way in the night sky over baobab trees in Madagascar

Capture the Atlas have announced their picks for the 2023 Milky Way Photographer of the Year competition. As usual, I’ve included a few of my favorites here โ€” from top to bottom: Jakob Sahner’s photo from the Canary Islands, Mihail Minkov’s composite shot of the Milky Way as it looks in both the summer & winter, and Steffi Lieberman amongst the baobab trees in Madagascar. Here’s Minkov explaining his full-galactic view:

I’ve always wondered what the night sky would look like if we could see the two Milky Way arches from the winter and summer side by side. This is practically impossible, since they are part of a whole and are visible at different times of the day.

However, this 360-degree time-blended panorama shows us what they would look like. The two arches of the Milky Way represent one object in the starry sky, with part of it visible in winter and part of it in summer. Therefore, they are called the winter and summer arches. The winter arch includes objects that we can observe from October to March, primarily associated with the constellation Orion.

On the other hand, the summer arch features the Milky Way core, visible from March to September, which is the most characteristic and luminous part of the night sky, representing the center of our galaxy.


New Massive Image of the Milky Way with 3.32 Billion Individual Objects

image of part of the Milky Way with 3.32 billion individually identifiable objects

small portion of an image of part of the Milky Way with 3.32 billion individually identifiable objects

Thanks to a planet-wide collaboration, scientists have released an image of the Milky Way that contains 3.32 billion individually identifiable objects, most of which are stars.

Gathering the data required to cover this much of the night sky was a Herculean task; the DECaPS2 survey identified 3.32 billion objects from over 21,400 individual exposures. Its two-year run, which involved about 260 hours of observations, produced more than 10 terabytes of data.

Most of the stars and dust in the Milky Way are located in its spiral disk โ€” the bright band stretching across this image. While this profusion of stars and dust makes for beautiful images, it also makes the galactic plane challenging to observe. The dark tendrils of dust seen threading through this image absorb starlight and blot out fainter stars entirely, and the light from diffuse nebulae interferes with any attempts to measure the brightness of individual objects. Another challenge arises from the sheer number of stars, which can overlap in the image and make it difficult to disentangle individual stars from their neighbors.

It’s worth checking out the largest size of the image published on the web (which is actually much smaller than the image’s actual size) as well as a tiny portion of the full image (second image above) that shows just how much detail is there. A zoomable interface for the entire image is available here.


The 2021 Milky Way Photographer of the Year

a photo of the Milky Way galaxy over a rocky canyon

a photo of the Milky Way galaxy over a house in the snow

To inspire folks to seek out their own galactic vistas, Capture the Atlas has chosen the best photos of the Milky Way for 2021. The top photo was taken by Daniel Thomas Gum in Australia and the bottom one by Larryn Rae in New Zealand. Check out the rest of the selections here.


Here’s What 10 Million Stars Look Like

10 Million Stars

Using the Dark Energy Camera at the Cerro Tololo observatory in Chile, astronomers took an image of the stars clustered around the center of our Milky Way galaxy that shows about 10 million stars. Check out the zoomable version for the full experience.

Looking at an image like this is always a bit of a brain-bender because a) 10 million is a huge number and b) the stars are so tightly packed into that image and yet c) that image shows just one tiny bit of our galactic center, d) our entire galaxy contains so many more stars than this (100-400 billion), and e) the Universe perhaps contains as many as 2 trillion galaxies. And if I’m remembering my college math correctly, 400 billion ร— 2 trillion = a metric crapload of stars. (via bad astronomy)


Behold Our Dazzling Night Sky When the Milky Way Collides with Andromeda in 4 Billion Years

This is what our night sky is going to look like in 3.9 billion years:

Milkdromeda

Wow! So what’s going on here? Using data from the Hubble Space Telescope, astronomers at NASA have predicted that our own Milky Way galaxy and the nearby Andromeda galaxy (M31) will collide about 4 billion years from now. As part of the announcement from 2012, they produced a video of what the collision would look like and a series of illustrations of what our sky will look like during the collision process.1

In 2 billion years, Andromeda will be noticeably closer in the sky:

Milkdromeda

By 3.75 billion years, it will fill a significant chunk of the sky. And the Milky Way will begin to bend due to the pull of gravity from Andromeda:

Milkdromeda

In about 3.85 billion years, the first close approach will trigger the formation of new stars, “which is evident in a plethora of emission nebulae and open young star clusters”:

Milkdromeda

Star formation continues 3.9 billion years from now. Could you imagine actually going outside at night and seeing this? It’s like a nightly fireworks display:

Milkdromeda

After the galaxies pass by each other in 4 billion years, they are stretched and warped by gravity:

Milkdromeda

In 5.1 billion years, Andromeda and the Milky Way will come around for a second close pass, their galactic cores blazing bright in the night sky:

Milkdromeda

And finally, in 7 billion years, the two galaxies will have merged into a single elliptical galaxy nicknamed Milkdromeda:

Milkdromeda

Interestingly, despite the galactic collision and the dazzling view from Earth, it’s extremely unlikely that any individual stars will collide because of the sheer amount of empty space in galaxies.

  1. I mean, assuming there will still be someone or something standing on the Earth 4 billion years from now to witness it. Presumably whoever’s around will have solved light pollution by then? The bigger worry is that according to the timeline of the far future, Earth will be uninhabitable long before an collision occurs (average surface temp of 296 ยฐF in 2.8 billion years). Toasty!โ†ฉ


The Entire Plane of the Milky Way Captured in a Single Photo

Entire Galaxy

By photographing two separate nighttime scenes, one in the northern hemisphere and the other in the southern hemisphere, amateur astrophotographer Maroun Habib cleverly produced this dazzling image of the complete galactic plane visible from Earth.

Is it possible to capture the entire plane of our galaxy in a single image? Yes, but not in one exposure โ€” and it took some planning to do it in two. The top part of the featured image is the night sky above Lebanon, north of the equator, taken in 2017 June. The image was taken at a time when the central band of the Milky Way Galaxy passed directly overhead. The bottom half was similarly captured six months later in latitude-opposite Chile, south of Earth’s equator. Each image therefore captured the night sky in exactly the opposite direction of the other, when fully half the Galactic plane was visible.

See also The Earth Rotating Beneath a Stationary Milky Way, which went viral after I posted it two weeks ago. (via @surfinsev)


The Earth Rotating Beneath a Stationary Milky Way

In most time lapse videos you see of the night sky, the stars wheel through the sky as the heavens revolve around the Earth. But that perspective is really only valid from our particular frame of reference standing on the Earth. What’s actually happening is that our tiny little speck of dirt is twirling amid a galactic tapestry that is nearly stationary. And in the video above, you see just that…the Earth rotating as the camera lens stays locked on a motionless Milky Way. Total mindjob.

See also the fisheye views of the Earth rotating about the stabilized sky in this video.

Update: Another time lapse of the Earth rotating underneath the stars:


A 20-year time lapse of stars orbiting a massive black hole

The European Southern Observatory’s Very Large Telescope in Chile has been watching the supermassive black hole in the center of our galaxy and the stars that orbit it. Using observations from the past 20 years, the ESO made this time lapse video of the stars orbiting the black hole, which has the mass of four million suns. I’ve watched this video like 20 times today, my mind blown at being able to observe the motion of these massive objects from such a distance.

The VLT was also able to track the motion of one of these stars and confirm for the first time a prediction made by Einstein’s theory of general relativity.

New infrared observations from the exquisitely sensitive GRAVITY, SINFONI and NACO instruments on ESO’s Very Large Telescope (VLT) have now allowed astronomers to follow one of these stars, called S2, as it passed very close to the black hole during May 2018. At the closest point this star was at a distance of less than 20 billion kilometres from the black hole and moving at a speed in excess of 25 million kilometres per hour โ€” almost three percent of the speed of light.

S2 has the mass of about 15 suns. That’s 6.6 ร— 10^31 pounds moving at 3% of the speed of light. Wowowow.