kottke.org posts about Milky Way

Here’s What 10 Million Stars Look Like

posted by Jason Kottke   Oct 28, 2020

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 × 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

posted by Jason Kottke   Oct 21, 2019

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


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:


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:


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”:


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:


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


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:


And finally, in 7 billion years, the two galaxies will have merged into a single elliptical galaxy nicknamed 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 °F in 2.8 billion years). Toasty!

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

posted by Jason Kottke   Aug 26, 2019

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 — 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

posted by Jason Kottke   Aug 16, 2019

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

posted by Jason Kottke   Jul 31, 2018

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 — almost three percent of the speed of light.

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