Back in November 2023, the Voyager 1 space probe — the most distant human-made space mission — suffered a serious malfunction. The cause is unknown (maybe a cosmic ray zapped it) but a chip on the Flight Data System computer stopped working. The FDS collects all the data from the instruments onboard and sends them to Earth, but all it was sending was gibberish. The good news: after diagnosing and working the problem, engineers figured out a way to bypass that chip, storing software on different parts of the FDS. It was complicated, but now Voyager 1 is sending data back to Earth once again. Over the next few months they expect they can redirect all the software so that they can return the venerable probe back to health. It was launched over 46 years ago and is currently over 24.4 billion kilometers from Earth, and still moving away at high speed. It’s technically in interstellar space, though also still within the realm of the solar system. It has power for many years to come, and is still taking measurements of the environment around it, providing valuable data to scientists about conditions at the edge of the Sun’s influence in the galaxy. So this is great news, and may it continue to function for many decades to come.

34 years ago yesterday, Hubble Space Telescope was launched into space.

To celebrate, astronomers have released this lovely image of a dying star blowing its guts out into space.

This is M76, the 76^th in Charles Messier’s catalog of objects that irritated him because he’d be scanning the skies looking for comets, and instead he’d find a faint fuzzy thing that was not a comet. The irony is that his list is a showcase of the brightest and best objects in the northern hemisphere skies to observe with small telescopes. Weirdly, I don’t recall ever seeing M76 for myself with my own ‘scope, which is surprising to me given its location between the stars in Andromeda and Cassiopeia, making it relatively easy to spot. It’s not up until winter, really, so I’ll have my chance again later this year.

So what is M76? When a star like the Sun dies, it expels its outer layers of gas, revealing material deeper and deeper in its interior. The star’s exposed core, at this point, is dense and very hot —we call it a white dwarf — lighting up that gas and making it glow as it expands away into space. The gaseous structure is called a planetary nebula, not because it necessarily has anything to do with planets, but because they tend to be small, somewhat disk-shaped, and greenish (excited oxygen atoms glow vigorously green, common in these objects), so they looks a bit like planets.

In this case, the gas is not expanding away in a sphere, but is instead a squashed hourglass-shape. That’s a telltale sign that there was probably a second star involved, likely a close companion in a binary relationship with the star in question. As the first star began dying and expanded into a red giant, it would have consumed its companion. The orbital speed of the second star around the first is likely faster than the first star rotates, so eating this companion would speed it up. As it rotated faster, it would throw off material in the plane of the second star’s orbit due to centrifugal force, similar to how you feel a force pushing you away from the center of a rapidly spinning merry-go-round.

So a lot of this material will form a thickish disk over the star’s equator that blows away into space. Later on in the star’s evolution is starts blowing a faster wind of matter, and this stuff slams into that ring and stops. But some of this stuff is blown from the star’s poles, up and down relative to the disk, and creates the double-lobed bubble. If this sounds familiar, I’ve written about Supernova 1987A’s disk and hourglass nebula many times, and the formation process is pretty similar (I explain that whole thing in a series of short posts from my Very Old Website).

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