If we graph the variability of a small bright star which is lined up with the asteroid belt, is it less constant than stars that are far away from the asteroid belt? To what degree does variability change relative to distance away from the most dense areas of the solar system?

I added the arrows to illustrate the question. enter image description here

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    $\begingroup$ I'm not sure I follow. The asteroid belt is part of our solar system, and closer than even the nearest non-solar star. $\endgroup$
    – user21
    Commented Dec 17, 2017 at 4:55
  • $\begingroup$ Thanks, ok I changed the wording, to a small bright star that is lined up with the asteroid belt rather than on it $\endgroup$ Commented Dec 17, 2017 at 5:07
  • $\begingroup$ You might want to update the title as well. I'm pretty sure the answer is going to be no. The only reason I can think of for increased variability would be occultations of stars by asteroids. Such occultations are likely to be rare, and they wouldn't be considered as variability anyway. $\endgroup$ Commented Dec 17, 2017 at 5:44
  • $\begingroup$ The occultations website sais that there are 100ds of occultations every night, so there are perhaps thousands of incomplete ones higher than 5%, and dozens of thousands of them which are barely detectable at 0-2% $\endgroup$ Commented Dec 17, 2017 at 6:11
  • $\begingroup$ Where does the image come from? $\endgroup$ Commented Dec 17, 2017 at 11:08

1 Answer 1


No, stars that are seen through the asteroid belt are not any more variable than stars in any other part of the sky.

All stars vary in brightness on measurable timescales, although some have been measured to have such small variations that they are recorded as "standard" stars and for most purposes can be considered to have a constant brightness and thus be used as reference for other brightness measurements.

What you are referring to, as noted, are occultations. There are many hundreds of thousands of known asteroids in our Solar System, and billions of stars in our galaxy, and so there could be hundreds of predicted occultation events every day, and there are many people interested in occultation events. For one thing, we can calculate the distance and speed of an asteroid quite accurately but we can't directly photograph it to determine its size. But when an asteroid passes in front of a star, we can measure the duration of the occultation and set precise limits on its size.

But for all the asteroids in the Main Belt, the space between them is huge and for any one star the chances of an occultation are quite (vanishingly) small, so the stars seen through the asteroid belt are not any more variable than anywhere else in the sky.

  • $\begingroup$ Are there really hundreds of predicted occultations every day? These are predictions for events viewable from Earth's surface at night? Or from survey instruments in orbit? I'm just curious. I see an average of 10/day on this list, but perhaps there's a more complete one? asteroidoccultation.com $\endgroup$
    – uhoh
    Commented Dec 18, 2017 at 3:54
  • $\begingroup$ Globally, yes, but if you narrow it down to a particular location, no. If I were to obtain a list of predictions with the intention of attempting observations, I would set limits on the probability for the track to pass across my geographic target area. This typically returns only a handful of high-probability events over a period of weeks. $\endgroup$
    – Mick
    Commented Dec 18, 2017 at 4:01
  • $\begingroup$ Can you include a link that shows 100 predictions for one day? $\endgroup$
    – uhoh
    Commented Dec 18, 2017 at 4:10
  • $\begingroup$ To be honest, the academics should have done a serious survey to quantify the number of occulations per day in various zones of the sky. If they video 100ds of stars from Chile, ok the chance of 1 occultation is not very high, but if there are perhaps 100 nightly and 1000 20-30% ones, 4-5 nights of surveying will bring back some statistics about how many precisely happen. Rather than relying on predicted models from known objects, the academics should directly measure fairly wide field videos. Perhaps it's not feasable though due to too many communications hastelites. $\endgroup$ Commented Dec 18, 2017 at 9:38
  • $\begingroup$ Cool answer, No references! I am not totally convinced that we are sure that there is not 1-2-10x multiplied asteroid related dimming events for a star that is precisely in line with the asteroid belt, given that all the asteroids there probably amount to having 1/50th slice of the moon at that band of space, I would love to know the total occlusion surface area of unkown objects there by way of scientific measurement. It must be graphable to a given factor of 10 using measurement. $\endgroup$ Commented Dec 18, 2017 at 10:02

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