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原始链接: https://news.ycombinator.com/item?id=40691042

Esasky 是一个在线平台，用户可以在其中访问来自世界各地天文台的天文数据。其界面具有多个控制选项。初始控件选择数据集或观测类型，覆盖天空的各个部分和多个波长范围。随后的控件允许用户探索特定的观察结果、编目对象信息和光谱数据。该平台还支持高级功能，例如用于表访问和光谱分析的 TAP 协议。虽然某些功能可能需要专业知识，但 Esasky 为天文学界的研究人员和爱好者提供了全面的资源。

Since no one has explained what esasky is: esasky allows professional astronomers (and anyone else because astronomy is all about open science) to view science observations from observatories across the world in one place.

If you look in the top-left corner you'll see a bunch of controls.

The first one (with three layers) chooses what is displayed. You can choose from loads of surveys (some which cover the whole sky, others that only cover a part) at loads of different wavelengths (and because the sky does change, search for LSST, there's an implicit time aspect as well). These are the original images (ignoring the underlying reduction process each survey does), these are for science not outreach. This is the button to play with (see how the same spot looks in visible vs. radio vs. x-ray).

Next button allows you to pick specific observations (as the all-sky part has implications about how you tessellate images), not that useful unless you understand what you're doing in more details than I have space for.

After that is catalogues of objects. This information will be compiled by survey teams, and is derived from various sources (including other catalogues). The magical astronomy keyword here is "TAP" for Table Access Protocol.

Spectra and timeseries is the next button, you're (generally) looking at spectra/timeseries from individual objects here, but things get more complex here.

The remaining buttons are really of no interest outside the profession sphere (though the multi-messager (i.e. not light, think gravitational waves/neutrinos etc.) button might be interesting when LIGO is running).

(I'm an astronomy RSE, but I don't work on esasky, nor for ESA).

Beautiful, but could do with using quaternions for rotation to avoid gimbal lock. At least I assume that’s the problem with getting stuck on the poles

For interactive navigation on a sphere (remember, this is just a sphere looked at from the inside) you actually want absolute euler angle based rotations, otherwise compound rotations around any closed loop on the sphere's surface will change the orientation of the camera and make further navigation extremely confusing. Source: many years spent designing 3d applications. Also, Google Earth and every other major app do it the same way.

Im fact, if you zoom out all the way, you'll see that we're actually looking at a sphere from the outside, as if the stars are situated on a celestial globe. It seems to be a relatively common convention for interactive night-sky maps.

Inverting the Z axis purely as a UI quirk/implementation detail is one thing, but more interesting would be to embrace it as a means of representing the time scale of the universe - as you zoom into the earth, you zoom into the deeply redshifted ancient data, which conveniently is from a smaller universe so projecting it onto a smaller shell of the sphere makes sense. Until you reach the core, which is a picture of the cosmic background radiation.

I'm confused why you think this is confusing? Stellarium is something you use to point a telescope with (and more focused on amateurs), whereas esasky is designed to browse through objects/images/spectra (with science data for scientists)? I don't know how much the overall data would be (given esasky is using a bunch of astronomy standards would be), but we're at least in 100s of PBs here.

I don’t see evidence of 100s of PB of data here. I do see multiple green stars, which I know is extremely rare in the real world. That’s just not a common color spectrum for stars.

And using a viewpoint of a large sphere from the outside just seems wrong. It should be viewed from the inside.

It's just a projection, you're looking at the sphere of the sky as seen from a (stabilized) Earth position. When you zoom out, you increase your field of view beyond that of the human eye to encompass the whole sphere. Because there's no way to compress a sphere into a plane, you have to choose a projection; this is a common projection (stereographic) which lets you zoom out as far as 180 degrees, by presenting the field of view as if it were the surface of a sphere as seen from an infinite distance.

exactly. I see it as well in multiple other spots as well. eg: 1. 05 49 04.008 +01 09 47.27 FoV: 1.3° X 2.2° 2. 05 44 35.074 +01 52 52.36 FoV: 3.4° X 5.9° 3. 06 37 17.795 -47 18 20.97 FoV: 1.4° X 2.4°

many more that i didnt list.

Pretty much everything beyond our solar system is essentially fixed on a human timescale. Over 2000 years, a typical star will move about half a degree. That's the width of the moon in the sky. There are of course notable exceptions like Barnard's Star, whose movement is pretty obvious on photographs taken over several decades.

If you want to explore how space changes over time, I recommend you look into something like Celestia[0]. It allows you to simulate star movement over thousands of years, and show you how the night sky looked to the Ancient Egyptians.

[0]: https://celestiaproject.space/

To quote [0]:

> Although snowflakes are all the same on an atomic level (they are all made of the same hydrogen and oxygen atoms), it is almost impossible for two snowflakes to form complicated designs in exactly the same way. While snowflakes can be sorted into about forty categories, scientists estimate that there are up to 10^158 snowflake possibilities. (That’s 10^70 times more designs than there are atoms in the universe!)

[0] https://ssec.si.edu/stemvisions-blog/are-all-snowflakes-real...

Maybe you could link to the images themselves rather than positions on the ESASky map? Those positions are associated with hundreds of thousands of images.

Does it not open properly on your end? The artefacts seem pretty glaringly obvious in those locations and I've tested the links in another browser to make sure it's not caching the zoom or whatever. What you see when you load is the image I'd take.

Anyhow, whoever can actually answer will surely know which ones I mean.

well... it's not always night time... it's not always clear skies.. it's not often that a power outage happens in my city to actually see the stars...

If this even remotely resembled “looking at the sky” I seriously doubt there would be much demand or response to it. Fortunately, for the less incurious among us anyway, that’s not what’s happening here.

To quote the immortal @butz quoting the very front page of the link…

> ESASky is an application that allows you to visualise and download public astronomical data.

To get a halfway-decent view of the night sky I'd have to drive about an hour away from my home. To get a good view of the night sky I'd have to fly to another country half a continent away.

Europe, I guess. Lots of technologically advanced countries with high urbanization rates and population density, none of the large swathes of undeveloped land in the middle like the US enjoys.

Light pollution has made damn sure that we don't know. If you live in a city (statistically extremely likely) it's a drive of few hundred km to a place where one can see anything remotely similar. If you're lucky.

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