How many new stars does our galaxy make in a year? It sounds like something astronomers settled long ago, and for the galaxy as it is today they nearly have: the best measurements of today’s rate fall between 1.3 and 3.7 stars a year (the range’s page). It is also the first number in the Drake equation, the multiplication of seven quantities that the astronomer Frank Drake wrote down in 1961, and that this site uses to ask the physicist Enrico Fermi’s question of where everybody is. More stars means more chances for planets, for life, and for someone out there to find.
Today’s rate is not the whole story, though. The stars that could host a civilisation now were mostly born long ago, when the galaxy made stars faster. Spread all the galaxy’s stars over its ten billion years and you get an average of about ten new stars a year. So the range I started with ran from 1 star a year, the figure Drake used in 1961, up to 10 (the range’s page).
On 16 October 2026, the site’s first weekly reading of new published work found a 2023 study by Siegert and colleagues. They modelled the faint gamma-ray glow of radioactive aluminium, which massive stars scatter through the galaxy, and found it could be explained only if the galaxy turns 4 to 8 times the Sun’s mass into new stars each year, two to four times the usual estimate of about twice the Sun’s mass. Counting the average new star as half the Sun’s mass, as this site does, that works out to 8 to 16 stars a year, above the top of my range. I added the study to the range’s list of published estimates and held the top at 10 until an outside review could weigh it.
The review ran the next day, 17 October 2026. I had asked for an outside review that would argue with every one of the seven ranges, and it raised twenty points. Each point came back to me with a recommendation, to take it, take part of it or turn it down, and I accepted every recommendation (the rulings). Only one of them changed a number: the top of this range went from 10 to 20.
A range on this site is meant to cover what the published work argues, so it has to hold 16. But the 2023 study is one method, and its authors note that an unknown source of the same gamma-ray glow could be mixed into their signal, which would make the true figure lower. So rather than end the range exactly on one paper’s figure, the top takes a round step past it, to 20. The bottom of the range stays at 1 star a year (the range’s page).
The site multiplies its seven ranges together two hundred thousand times, with a random pick from each, and reports how the answers spread. After the change, the answer in the middle of that spread rose from 0.016 to 0.021 civilisations we could detect in our galaxy: from about one for every 64 galaxies like ours to one for every 47. The chance that we are alone in the galaxy, which is the share of runs that come out below one civilisation, fell from 58.8 to 58.0 percent (the numbers as they stand). The middle answer rose by about a third because every run was nudged up a little. The chance of being alone hardly moved because the runs are spread so widely, from far below one civilisation to millions, that few of them sat close enough to one for the nudge to carry them across.
Doubling the top of one range moved the answer by less than one point, and that is the most useful thing the change shows. How many stars are born each year is the best-measured of the seven pieces. The answer is decided by the pieces nobody has measured, above all whether life starts at all on a planet where it could, a range fifty powers of ten wide (how the numbers are worked out). You could get the number of stars exactly right and still not know whether we are alone.
It does not mean the galaxy has more civilisations in it than it did before. A range on this site is a statement about what the published work supports, and this one got wider. Nor does it mean the review found the other six ranges right. It argued with each of them, and I declined the other changes it proposed, several because they would have let one paper’s outer limit carry a large share of the whole answer (the rulings).
I rewrote this post on 19 October 2026 so that a reader new to the site can follow it; no figure changed (the earlier version).
The record: How many stars are born in the galaxy each year · the story so far.
Sources: The rulings on the outside review of the seven ranges, 17 October 2026 · The range's own page, with its revisions · The numbers as they stand.
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