We’ve got a good idea of how many stars we can see at night but that doesn’t tell us how far away they are.
We also know how to measure the distance to a star, but that doesn’t help us answer how many suns are within 100 light-years of our solar system.
Since we wanted to know the answer, we went ahead and counted, using our favorite astronomy software SkySafari 6.
Method
Of course, you want the answer to your question but stick with us one minute while we explain how we got to the answer, and then we’ll share all the relevant data we’ve compiled.
SkySafari 6 is an astronomy app that holds lots of data on each of millions of stars. Helpfully for us, they also have a search function that lets you specify what it is you’d like to observe.
We counted the number of stars in bands of distance from Earth measured in light-years (find out what a light-year is, opens a new tab). The bands we used to gather the data are:
- 100 light-year intervals from 0 to 2,999 light-years
- 250 light-year intervals from 3,000 to 4,999 light-years
- 1000 light-year intervals from 5,000 to 9,999 light-years
We carried out a simple count of all the stars in the database and a separate count of the stars brighter than relative magnitude 6.0 because these are visible to the naked eye under a dark sky.
Data Limitations
There are two limitations to the data which we need to point out before we let rip with our findings.
- SkySafari Pro has data for stars only to magnitude 15. For our purposes, this is fine because an average backyard telescope can’t see fainter stars. However, whereas we would see the number of all stars growing the further from Earth we get, what we actually see is a declining number because of this limiting magnitude.
- The software’s database only includes distance information for stars within 10,000 light-years. There are stars brighter than magnitude 15 beyond this distance but they are not included in our survey.
With all that said, let’s move on to the main business.
How Many Stars Within 100 Light-Years of Earth?
There are 59,722 stars visible with a telescope within 100 light-years of our solar system. Of these, 471 shine at magnitude 6.0 or brighter, making them visible to the naked eye under a dark sky.
If you’re anything like us, that answer alone won’t have come close to satisfying your curiosity. Or, it has, but a load of new questions has been set off in your mind.
Let us share our data with you and have a dive into the facts and figures behind it all.
The Number of Stars Within 3,000 Light-Years of Our Solar System
We counted the number of stars, including all the different types of star, within 3,000 light-years of Earth on 100 light-year intervals.
While we were at it, we also counted the number of suns visible to the naked eye, i.e. those brighter than magnitude 6.0.
You can see our data table below. Underneath that, we’ll summarize the more interesting insights.
Working from left to right, the first column shows the distance from Earth. You can see the 100 light-year intervals, e.g. 0-99.9 ly, then 100-199.9 ly, and so on.
The next two columns cover all stars to magnitude 15.0. The first of these is a count within the band, the second is a running total of all stars.
The last two columns do the same thing but this time only for stars we can see with the naked eye, i.e. those of magnitude 6.0 and brighter.
Take the 900-999.9 light-years row to work through as an example. Within that 100 light-year band, there are 8,750 stars altogether. That brings the running total to 271,732, i.e. that’s the total number of stars within 999.9 light-years of Earth.
Moving to the right, we can see there are 97 naked-eye stars within the same band, bringing the running total to 4,542.
Data Insights – All Stars
A table of that size is not immediately easy to interpret, so let’s break it out into a couple of separate charts. This first one shows the total number of stars in each 100 light-year bands.
We can see that the number of stars we can see with a telescope drops rapidly with the distance. We could have guessed that would happen, after all, generally, the further away a star is, the dimmer it is, but the rate is a surprise.
There are around 60,000 stars within 100 light-years, and the same again with 100-200 light-years, and then the numbers fall quickly.
By the time we’re 1,000 light-years out, there are fewer than 8,000 stars and, at 1,300 light-years, fewer than 5,000 stars. The curve in the chart gradually flattens from there onwards, ending with fewer than 2,000 stars in each 100 light-year interval from 2,600 light-years.
Data Insights – Naked-Eye Stars
This second chart shows the number of stars visible to the naked eye for every 100 light-years ‘shell’ around the Earth, out to 3,000 light-years away.
There are just shy of 500 brighter stars within 100 light-years of us, which ramps up to 842 between 100 and 200 light-years away. Then, just as with all the stars, there is a quick decline to below 100 stars when we’re 1000 light-years distant.
It should come as no surprise that there aren’t many stars more than 1000 light-years away that are visible to the naked eye here on Earth. If anything, we were shocked to learn that some stars are so bright that even when they are over 2,500 light-years away, there are still 49 that we can see with the naked eye.
How Many Stars Within 1000 Light-Years of Earth?
There are 271,732 stars within 1,000 light-years of Earth which are visible in a backyard telescope. Of those, 4,542 are brighter than magnitude 6.0 and visible to the naked eye.
As we move further out from Earth, there are fewer suns visible in our telescopes. The following summarizes the numbers out to 3,000 light-years:
- Upto 500 light-years away = 207,773 stars
- Between 500 and 1000 ly = 63,939 stars
- 1000-1500 ly = 27,892 stars
- 1500-2000 ly = 17,013 stars
- 2000-2500 ly = 12,478 stars
- 2500-3000 ly = 7,490 stars
The same holds true for stars visible to the naked eye, i.e. those that shine brighter than magnitude 6.0:
- Upto 500 light-years away = 3,875 stars
- Between 500 and 1000 ly = 1,026 stars
- 1000-1500 ly = 286 stars
- 1500-2000 ly = 126 stars
- 2000-2500 ly = 59 stars
- 2500-3000 ly = 49 stars
The Number of Stars Between 3,000 and 5,000 Light-Years From Our Solar System
We’re moving much further out in this next section.
This bunch of stars is so far away that it takes their light between 3,000 and 5,000 years to reach us. There is still plenty of stars we can see in our telescopes and even some that we can see with the unaided eye.
Let’s start with a look at our data table for this group.
The column format is the same as used above, so we won’t explain it again here, other than to note that the ‘Running Total’ columns carry on from the previous total.
For example, on the 3750-3749.9 row, there is a running total figure of 340,092 stars. This is the total number of stars within 3749.9 light-years of our planet.
The number of stars in every 250 light-years ‘shell’ diminishes considerably after 3,500 light-years; there are fewer than 200 per shell from 4,250 light-years out.
Remarkably, there is still a handful of naked-eye stars beyond 4,000 light-years from us. These are:
- Alpha Camelopardalis, magnitude 4.3
- Kappa Cassiopeiae, 4.2
- Nu Cephei, 4.3
- I Puppis, 4.0
- 41 Geminorum, 5.7
- 10 Sagittae, 5.7
- HR 3291 (Puppis), 5.9
- HR 7055 (Scutum), 5.7
How Many Stars Within 5000 Light-Years of Earth?
There are 340,810 stars within 5,000 light-years of Earth which are visible in a backyard telescope. Of those, 5,084 are brighter than magnitude 6.0 and visible to the naked eye.
As we move beyond 3,000 light-years from Earth, there are significantly fewer stars visible to our telescopes. In fact, more than 98% of all the stars our scopes can see are closer than that.
The following summarizes the numbers out to 5,000 light-years:
- Between 3000 and 3500 ly = 2,859 stars
- 3500-4000 ly = 628 stars
- 4000-4500 ly = 410 stars
- 4500-5000 ly = 308 stars
The same holds for stars visible to the naked eye, only more so. Less than 1% of all the stars that shine brighter than magnitude 6.0 are more than 3,000 light-years from us:
- Between 3000 and 3500 ly = 15 stars
- 3500-4000 ly = 2 stars
- 4000-4500 ly = 4 stars
- 4500-5000 ly = 1 star
The Number of Stars More Than 5,000 Light-Years from Earth
Technically, we’re looking at stars between 5,000 and 10,000 light-years distant because we don’t have distance data for stars further away than that.
However, as the table below suggests, there are very few stars we can see that are beyond that distance, even with a high-quality backyard telescope.
In the first 5,000 light-years from Earth, we encounter 340,810 stars brighter than magnitude 15.0. The next 5,000 light-years, i.e. from 5,000 to 10,000 light-years away, contains just 1,675 stars that we can see with a telescope.
That means that only 0.5% of all the stars that we could see through a large hobby telescope are more than 5,000 light-years away. In other words, practically every star you see when doing astronomy is closer than 5,000 light-years away.
When you consider that our galaxy, the Milky Way, is believed to be 100,000 light-years across, you realize that we can usefully only see individual stars about 10% of the way across it (5% in each direction from Earth).
Let’s finish with a quick note on the stars visible to the naked eye at this distance. It’s a safe bet that the 26 stars we can see unaided from more than 5,000 light-years away are either very large, very bright, or both.
The eleven most distant stars that we can see unaided are:
- x Carinae, magnitude 3.9
- Theta Muscae, 5.7
- 15 Sagittarii, 5.3
- V371 Carinae, 5.2
- V524 Carinae, 5.3
(most distant at 9,700 light-years, southern hemisphere only) - GX Velorum, 5.0
- HR 3496 (Vela), 5.8
- HR 4887 (Crux), 5.8
- HR 5036 (Centaurus), 5.8
- HR 6716 (Sagittarius), 5.8
- HR 7589 (Cygnus), 5.6
The most distant star visible to the naked eye from the northern hemisphere is HR 7589 in Cygnus. It is 7,600 light-years from Earth.
We’ve highlighted HR 7589 in the SkySafari 6 chart above. Try looking for it under a dark sky next time the constellation of Cygnus flies high, and wonder at seeing the most distant star visible to the naked eye.
How Many Stars Within 10,000 Light-Years of Earth?
There are 342,485 stars within 10,000 light-years of Earth which are visible in a backyard telescope. Of those, 5,110 are brighter than magnitude 6.0 and visible to the naked eye.
Looking out beyond 5,000 light-years from Earth for individual stars is an increasingly fruitless exercise. Even with a respectable backyard telescope, fewer than one in 200 of the stars you can see are further away than this.
The following summarizes the numbers out to 5,000 light-years:
- Between 5,000 and 10,000 ly = 1,675 stars
(equivalent to 0.49% of all the stars we can see)
Amazingly, however, there is a tiny group of 26 stars that are more than 5,000 light-years away but still visible to the naked eye. All except four of them are within 8,000 light-years of us, including the most distant one we can see from the northern hemisphere.
- Between 5,000 and 10,000 ly = 26 stars
(equivalent to 0.51% of all the visible stars we can see)
Summary
This has been a great voyage of discovery for us and we hope you found that it scratched your knowledge itch.
We discovered that practically all of the stars we can see, either with our unaided eyes or in a telescope, are within 5,000 light-years of us. 80% of the stars we enjoy looking at are within 1,000 light-years of our solar system.
Ultimately, this is perhaps not a surprise since we’re more likely to see suns that are closer to us. However, we enjoyed learning where to see a star with our naked eye which is more than 7,500 light-years away.
What puts us firmly in our place is realizing that even a very powerful telescope can only show us detail for about 5% of the galaxy we call home.
