This issue astronomers have with Starlink is not with increased light pollution per se, where the effect is negligible, but with the fact that when there are 10,000 of these in the sky at one time, it will be much more difficult to point a telescope and not have one of your exposures contaminated by a Starlink satellite passing through. Some telescopes will sit on a source for hours for the faintest objects and the odds of encountering one of these becomes worrisome.
Anything visible to the naked eye or even binoculars is honking bright to modern astronomical telescsopes, which are sensitive to sources millions of times fainter. Even if they're not directly in the field, off-axis reflections and glints can contaminate exposures. A train of these moving through the field would be a total disaster.
For those saying let's just build space-based telescopes, sure, but it's 10-100X more expensive, and even modest ground-based facilities produce 100GB/night these days, and you can't do that from space (yet).
On the bright side Starlink is something that can help to solve both of this issues by helping to lower the price of rockets and by improving the antennas.
> For those saying let's just build space-based telescopes, sure...
Weird idea: add some kind of telescope thing to the back of each Starlink satellite. Wonder if it'd be feasible to make up for the lower quality (of each small telescope) by the earth sized potential aperture? :)
If there is one within 1 AU of the Sun at any given time, then there are ~10^16 of them within a sphere out to the nearest star. I'll leave it to you to decide whether that's teeming or not.
Dr. Denneau, what an honor that you dropped by this comment thread! Congratulations on the publication, it's a truly groundbreaking discovery :) 10^16 is pretty mindbogglingly huge, but then again so is 4 light years...
Surely they're more dense near the sun? Not sure you can assume a uniform spacing and not account for the gravitational attraction. But I'm sure you know more about this than I do.
Co-author here. We obtained spectroscopic measurements of 'Oumuamua, and its surface closely matches D-type asteroids and comet nuclei, which are dark, reddish and organic-rich.
The spectroscopy seems pretty normal, but the shape is kinda freaking me out. If there were a single other object we'd ever seen which looks like this, that'd be different. But this seems really unique.
Is there a point where you, as a sober professional, start to entertain outlandish theories about something like this? Has this crossed that threshold?
If you wanted to disguise a probe, it seems the ideal form would be a black body, not to disguise it as an asteroid, I would guess. Unless they're playing mind games.
Anyways, given all the EM radiation we're tossing out into the void, some species' probe out there is going to pick up our existence sooner or later.
And at ~395 earth-moon distances it's difficult to imagine how effective a 400-meter object, disguised as an asteroid, would be at seeing much detail on earth.
But it is tantalizing and fun to imagine--the appearance of a gravity boost... Flat surfaces... Near to earth... Lack of any ice or outgasing, a solid object, many characteristics not seen in other known-asteroids, rotating on its long axis... :)
> And at ~395 earth-moon distances it's difficult to imagine how effective a 400-meter object, disguised as an asteroid, would be at seeing much detail on earth.
Ah, but it's a carrier for the small, stealthy probes!
Gravitational wave detection is nowhere near the first step to any sort of warp drive. In fact it is looking the like the nail in the warp drive coffin. I, and no doubt many others here, was hoping the new detectors would be picking up all sorts of tiny wave sources buzzing around us, a civilization of warp drives just beyond our previous limits of observation. But no, no tiny warp signatures. We are still alone. If ET is in our local galaxy he isn't using warp drives, only reducing their possibility.
Comet Shoemaker-Levy 9 in 1994. The comet had been captured decades earlier after entering Jupiter's Roche limit and was actually in orbit around Jupiter.
Collisions in the main asteroid belt have been observed, but only after impact. The signature is a puff of dust from the impact that fades after hours or days as the dust spreads. The statistics are imprecise, but collisions between kilometer-scale asteroids might have decades or hundreds of years between them.
Impacts are rare though. There's a reason they call it space. If you were standing on an asteroid in the main belt, the nearest asteroid to you would be so far away that you could not see it.
This article is way overthinking it. It's better to simply store the UTC time of the event, and nothing else. Local time zone conversions can be done when displaying/editing. Presumably at the time you are reading your calendar, your local software knows the current rules to offset from GMT.
We have Skype meetings all the time involving parties in different US timezones and/or different countries. There's no "place" or local time zone for the meeting. We schedule in UTC and our local software or calendar program knows what time zone we are in to display the correct local time.
> It's better to simply store the UTC time of the event, and nothing else. Local time zone conversions can be done when displaying/editing.
That timezone conversion is the problem, the UTC offset of a physical location can change drastically with surprisingly little notice. You schedule a meeting on your calendar for 10AM, it's stored as XUTC, the rules changes now your calendar tells you your meeting is at 11AM local time, you've missed your meeting (because you were physically meeting your VC who uses their own calendar which does not have that specific issue).
And being an hour off is pretty tame, back in 2011 Samoa flipped across the international date line, if you had scheduled a meeting after the flip and it was stored in UTC but edited or viewed in local time you would now go to it a day off.
I don't think you understood the described problem with storing the time in UTC. In the example in the article it is assumed and your software gets the timezone update. But because the meeting is stored in UTC, it displays the wrong time.
The reason it works for you is because you schedule in UTC. That's great, but for people that don't schedule meetings in UTC, you are vulnerable to the problem described if you just save the time in UTC.
Do you schedule meetings with your dentist in UTC too? I'd wager that most meetings are not scheduled in UTC.
Until today, I thought the way you did and advocated the same principle whenever I could. This article changed my mind very quickly, all with a simple easy-to-understand example.
For any event you generally have a location or time zone that the event time is specified in. If that's UTC then great, you don't have a problem. Most people don't work in UTC; if the time zone laws change, then the event time in UTC will change too.
"It's better to simply store the UTC time of the event, and nothing else."
The whole point of the article is that /you cannot know with certainty the UTC time of a future event/ if you are starting with a wallclock time in a particular location.
In this article, a 10:00 am meeting in Santiago has one UTC value prior to a new law, and a different UTC value after the new law.
If you are saying everyone should "schedule in UTC" like you do, good luck imposing that on the world!
What he's getting at is that timezone rules change, so the function to go from local to UTC when you save the meeting is not the same as the function to go from UTC back to local at the time of the meeting.
I do get the point, but simply preserving the local time isn't the right answer. I'd argue that when you change your local timezone offset, then your future schedule is indeterminate and all events have to be reverified. What if the event is for an international flight -- is it still leaving or arriving at the same local time? How about that standing 9AM meeting -- is at 9 because of the corporate office in a different time zone calls in, so your local time breaks their calendar?
Anything visible to the naked eye or even binoculars is honking bright to modern astronomical telescsopes, which are sensitive to sources millions of times fainter. Even if they're not directly in the field, off-axis reflections and glints can contaminate exposures. A train of these moving through the field would be a total disaster.
For those saying let's just build space-based telescopes, sure, but it's 10-100X more expensive, and even modest ground-based facilities produce 100GB/night these days, and you can't do that from space (yet).