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    <description>RSS Feed for Wolfram Community showing any discussions tagged with Astronomy sorted by active.</description>
    <items>
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        <rdf:li rdf:resource="https://community.wolfram.com/groups/-/m/t/3716438" />
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        <rdf:li rdf:resource="https://community.wolfram.com/groups/-/m/t/3686348" />
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        <rdf:li rdf:resource="https://community.wolfram.com/groups/-/m/t/3672762" />
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  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3716438">
    <title>Painting a Kerr black hole: a backward null-geodesic ray tracer with a real astrophotograph</title>
    <link>https://community.wolfram.com/groups/-/m/t/3716438</link>
    <description>![Painting a Kerr black hole: a backward null-geodesic ray tracer with a real astrophotograph][1]&#xD;
*&amp;#034;Hook image: a viewport screenshot from inside an interactive Wolfram viewer, looking at a 360-degree black-hole panorama generated by OpenAI&amp;#039;s gpt-image-2. This is AI art -- striking, but not derived from general relativity. The rest of the notebook builds the same scene from physics, in pure Wolfram Language. See Section 11 for the viewer itself.&amp;#034;*&#xD;
&#xD;
&amp;amp;[Wolfram Notebook][2]&#xD;
&#xD;
&#xD;
  [1]: https://community.wolfram.com//c/portal/getImageAttachment?filename=PaintingaKerrblackhole.jpg&amp;amp;userId=20103&#xD;
  [2]: https://www.wolframcloud.com/obj/1cc09d34-423c-4144-9e2c-c256740295ad</description>
    <dc:creator>Marco Thiel</dc:creator>
    <dc:date>2026-05-15T09:49:06Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3716185">
    <title>Aliens? Or weather balloons? You decide!</title>
    <link>https://community.wolfram.com/groups/-/m/t/3716185</link>
    <description>![Aliens? Or weather balloons? You decide!][1]&#xD;
&#xD;
&amp;amp;[Wolfram Notebook][2]&#xD;
&#xD;
&#xD;
  [1]: https://community.wolfram.com//c/portal/getImageAttachment?filename=AliensOrWeatherBalloonsYouDecide.jpg&amp;amp;userId=20103&#xD;
  [2]: https://www.wolframcloud.com/obj/a9f85d83-9d1a-47dc-92bc-bf3cfa1232c4</description>
    <dc:creator>Arnoud Buzing</dc:creator>
    <dc:date>2026-05-15T00:20:07Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3636637">
    <title>Gravity and Action from the Evolution of a Complex Manifold</title>
    <link>https://community.wolfram.com/groups/-/m/t/3636637</link>
    <description>&amp;amp;[Wolfram Notebook][1]&#xD;
&#xD;
&#xD;
  [1]: https://www.wolframcloud.com/obj/2eb2cb4e-4a63-4a59-a5e4-d983775859c3</description>
    <dc:creator>Donald Airey</dc:creator>
    <dc:date>2026-02-08T20:17:36Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3715214">
    <title>Google Earth Engine (GEE) paclet: satellite imagery fundamentals</title>
    <link>https://community.wolfram.com/groups/-/m/t/3715214</link>
    <description>&amp;amp;[Wolfram Notebook][1]&#xD;
&#xD;
&#xD;
  [1]: https://www.wolframcloud.com/obj/f3cc5b88-f290-4e68-ac29-2d450c373fd1</description>
    <dc:creator>Diego Zviovich</dc:creator>
    <dc:date>2026-05-12T23:08:24Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3714827">
    <title>Google Earth Engine (GEE) client paclet</title>
    <link>https://community.wolfram.com/groups/-/m/t/3714827</link>
    <description>![Google Earth Engine (GEE) client paclet][1]&#xD;
&#xD;
&amp;amp;[Wolfram Notebook][2]&#xD;
&#xD;
&#xD;
  [1]: https://community.wolfram.com//c/portal/getImageAttachment?filename=10966GoogleEarthEngine%28GEE%29clientpaclet.jpg&amp;amp;userId=20103&#xD;
  [2]: https://www.wolframcloud.com/obj/2a2947bc-b39e-494c-9309-173af5069ad5</description>
    <dc:creator>Diego Zviovich</dc:creator>
    <dc:date>2026-05-12T01:32:46Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3714638">
    <title>Counting AdS Vacua</title>
    <link>https://community.wolfram.com/groups/-/m/t/3714638</link>
    <description>&amp;amp;[Wolfram Notebook][1]&#xD;
&#xD;
&#xD;
  [1]: https://www.wolframcloud.com/obj/69a3596e-883a-4663-b088-21e5944d9a48</description>
    <dc:creator>Zihni Kaan Baykara</dc:creator>
    <dc:date>2026-05-11T15:31:12Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3712435">
    <title>Snyder&amp;#039;s Lorentz-covariant quantum spacetime</title>
    <link>https://community.wolfram.com/groups/-/m/t/3712435</link>
    <description>&amp;amp;[Wolfram Notebook][1]&#xD;
&#xD;
&#xD;
  [1]: https://www.wolframcloud.com/obj/d265c46a-003e-4024-80bd-f4e249f39a50</description>
    <dc:creator>Mohammad Bahrami</dc:creator>
    <dc:date>2026-05-05T19:57:28Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3706203">
    <title>Learning the Hertzsprung-Russell diagram: machine learning classification of stellar evolution</title>
    <link>https://community.wolfram.com/groups/-/m/t/3706203</link>
    <description>&amp;amp;[Wolfram Notebook][1]&#xD;
&#xD;
&#xD;
  [1]: https://www.wolframcloud.com/obj/1ad1af94-9785-4367-b665-21c66f5a4045</description>
    <dc:creator>Lim Lee</dc:creator>
    <dc:date>2026-04-27T04:06:18Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3711592">
    <title>Faster and more accurate than FLRW at predicting SNe Ia distances</title>
    <link>https://community.wolfram.com/groups/-/m/t/3711592</link>
    <description>This formula is more accurate at predicting SNe Ia comoving distances than FLRW and since it&amp;#039;s analytical, it will execute upwards of 10,000 faster and give you machine precision.&#xD;
&#xD;
$D_C(z) = \frac{t_o\left(2V_0 - A t_o\right) z}{2 + z}$&#xD;
&#xD;
![enter image description here][1]&#xD;
&#xD;
That&amp;#039;s it. That&amp;#039;s all there is to it. Here&amp;#039;s how it compares to FLRW:&#xD;
&#xD;
![enter image description here][2]&#xD;
&#xD;
Red is the analytical formula, blue is FLRW. Using the full covariance matrix of the Pantheon+ SH0ES project, the reduced $\chi^2$  of 1.68 for the analytical formula is significantly better than 2.49 for the numerical FLRW solution.&#xD;
&#xD;
This is an outrageous claim, so it should be easy to debunk. The full paper is here: [Acceleration Law Article][3] and the notebook is here: [Acceleration Law Notebook][4]. I&amp;#039;d appreciate your feedback, positive or negative.&#xD;
&#xD;
&#xD;
  [1]: https://community.wolfram.com//c/portal/getImageAttachment?filename=Screenshot2026-05-04204344.png&amp;amp;userId=20103&#xD;
  [2]: https://community.wolfram.com//c/portal/getImageAttachment?filename=HubbleDiagram.png&amp;amp;userId=3608757&#xD;
  [3]: https://www.wolframcloud.com/obj/de2ae88c-5ea9-4334-8b9c-3edbbac38fa5&#xD;
  [4]: https://www.wolframcloud.com/obj/ed737c03-5baf-49f4-90e3-83b91b245c2a</description>
    <dc:creator>Donald Airey</dc:creator>
    <dc:date>2026-05-04T19:36:36Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3675919">
    <title>Constraint vs search: why is evolution computationally tractable?</title>
    <link>https://community.wolfram.com/groups/-/m/t/3675919</link>
    <description>**Intro**&#xD;
&#xD;
A fundamental question keeps coming up for me:&#xD;
If biological evolution operates in astronomically large spaces, why is search computationally tractable at all?&#xD;
Even a modest protein corresponds to a combinatorial space that is effectively impossible to exhaustively explore. Yet evolution does not behave like an unconstrained random search.&#xD;
So what makes the space navigable?&#xD;
&#xD;
**Essay**&#xD;
&#xD;
In 1859, two different perspectives on complexity emerged.  &#xD;
Bernhard Riemann revealed deep structural order underlying the distribution of prime numbers.&#xD;
Charles Darwin introduced a dynamical process of variation and selection.  &#xD;
Modern biology has successfully developed Darwin’s framework. However, something is often left implicit: the assumption that the search space is already structured in a way that makes local exploration effective.  &#xD;
From a purely combinatorial perspective, this is problematic. Under simple assumptions (independent variation, no bias), expected search time grows exponentially with the amount of required information. In that regime, evolution would be computationally intractable.&#xD;
But real systems do not operate in that regime.  &#xD;
Instead, they appear to evolve within a highly structured, constrained subspace, where:  &#xD;
functional states are not isolated  &#xD;
viable configurations form connected regions  &#xD;
local mutations can traverse meaningful paths  &#xD;
This suggests that evolution can be framed as a constrained search problem, rather than a purely stochastic process.  &#xD;
Evolution is not merely a process acting within a space &amp;#x2014; it is a process shaped by the structure of the space it can access.  &#xD;
This shifts the central question:  &#xD;
What determines that accessible space?  &#xD;
&#xD;
**A Minimal Computational Model**&#xD;
&#xD;
To make this concrete, consider a simple toy model.  &#xD;
We define:  &#xD;
a sequence space  &#xD;
a mutation operator  &#xD;
a constraint that restricts transitions&#xD;
&#xD;
**Basic setup**&#xD;
&#xD;
    L = 20;&#xD;
    randomSeq[] := RandomInteger[{0, 1}, L];    &#xD;
    mutate[s_] := ReplacePart[s, RandomInteger[{1, L}] -&amp;gt; 1 - #] &amp;amp; @ s;&#xD;
&#xD;
&#xD;
&#xD;
**Fitness function**&#xD;
&#xD;
    fitness[s_] := Boole[Total[s] &amp;gt; 12];&#xD;
&#xD;
&#xD;
**Constraint energy**&#xD;
&#xD;
    energy[s_] := Total[&#xD;
      Map[If[# === {1, 1}, 0, 1] &amp;amp;, Partition[s, 2, 1]]&#xD;
    ];&#xD;
&#xD;
&#xD;
**Dynamics: constrained vs unconstrained**&#xD;
&#xD;
    stepConstrained[s_] := Module[{s2 = mutate[s]},&#xD;
      If[constraint[s, s2], s2, s]&#xD;
    ];&#xD;
    &#xD;
    stepRandom[s_] := mutate[s];&#xD;
&#xD;
**Search experiment**&#xD;
&#xD;
    findFunctional[step_, max_] := Module[&#xD;
      {s = randomSeq[], t = 0},&#xD;
      &#xD;
      While[t &amp;lt; max &amp;amp;&amp;amp; !TrueQ[fitness[s] == 1],&#xD;
        s = step[s];&#xD;
        t++;&#xD;
      ];&#xD;
      &#xD;
      t&#xD;
    ];&#xD;
    &#xD;
    trialsConstrained = Table[&#xD;
      findFunctional[stepConstrained, 1000],&#xD;
      {50}&#xD;
    ];&#xD;
    &#xD;
    trialsRandom = Table[&#xD;
      findFunctional[stepRandom, 1000],&#xD;
      {50}&#xD;
    ];&#xD;
&#xD;
**Visualization**&#xD;
&#xD;
    Histogram[&#xD;
      {trialsRandom, trialsConstrained},&#xD;
      ChartLegends -&amp;gt; {&amp;#034;Random&amp;#034;, &amp;#034;Constrained&amp;#034;},&#xD;
      PlotTheme -&amp;gt; &amp;#034;Scientific&amp;#034;,&#xD;
      Frame -&amp;gt; True&#xD;
    ]&#xD;
&#xD;
**Interpretation**&#xD;
&#xD;
In many runs, the constrained dynamics reaches functional states faster &amp;#x2014; not because the system is explicitly guided toward a target, but because the structure of the space itself has changed.  &#xD;
Even in this minimal model, a key effect emerges:  &#xD;
Pure random mutation behaves like unstructured search  &#xD;
Even a simple constraint dramatically reshapes accessibility  &#xD;
The constraint does not “guide” the system toward solutions. Instead, it reshapes the space such that functional paths become possible in the first place.&#xD;
&#xD;
**Open Questions**&#xD;
&#xD;
This raises several structural questions:&#xD;
&#xD;
- How can we formally define a constraint operator in general systems?  &#xD;
- Can constraint-induced subspaces be measured or classified?  &#xD;
- How does connectivity emerge in high-dimensional spaces under constraints?  &#xD;
- Do constrained systems exhibit characteristic spectral signatures (e.g., non-random eigenvalue statistics)?&#xD;
&#xD;
**Closing Thought**&#xD;
&#xD;
The difference between intractable search and effective evolution may not lie in time or randomness &amp;#x2014; but in the geometry of the accessible space itself.</description>
    <dc:creator>Maurice Crutzen</dc:creator>
    <dc:date>2026-04-07T09:31:01Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3710432">
    <title>Computational geometry modeling of the neolithic circular ditch in Vinoř, Prague</title>
    <link>https://community.wolfram.com/groups/-/m/t/3710432</link>
    <description>![Computational geometry modeling of the neolithic circular ditch in Vinoř, Prague][1]&#xD;
&#xD;
&amp;amp;[Wolfram Notebook][2]&#xD;
&#xD;
&#xD;
  [1]: https://community.wolfram.com//c/portal/getImageAttachment?filename=ComputationalgeometrymodelingoftheneolithiccircularditchinVino%C5%99,Prague2.jpg&amp;amp;userId=20103&#xD;
  [2]: https://www.wolframcloud.com/obj/97db78e9-ef10-4f2f-8506-9a77b82eff35</description>
    <dc:creator>Jessica Alfonsi</dc:creator>
    <dc:date>2026-05-01T15:59:22Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3706027">
    <title>Warp drives: symbolic tensor analysis of general-relativistic bubbles and energy conditions</title>
    <link>https://community.wolfram.com/groups/-/m/t/3706027</link>
    <description>&amp;amp;[Wolfram Notebook][1]&#xD;
&#xD;
&#xD;
  [1]: https://www.wolframcloud.com/obj/9823b1a8-b2fd-491e-83d0-5ee54badd179</description>
    <dc:creator>Marco Thiel</dc:creator>
    <dc:date>2026-04-26T19:39:43Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3707090">
    <title>European Space Agency&amp;#039;s Gaia mission data release 3: TAP client, 38 science charts, and dynamic GUI</title>
    <link>https://community.wolfram.com/groups/-/m/t/3707090</link>
    <description>&amp;amp;[Wolfram Notebook][1]&#xD;
&#xD;
&#xD;
  [1]: https://www.wolframcloud.com/obj/6473f01c-b05e-47e9-b7e6-eb1be887dd10</description>
    <dc:creator>Marco Thiel</dc:creator>
    <dc:date>2026-04-28T14:30:05Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3701280">
    <title>Exploring NASA SkyView: live imagery, dark-nebula analysis, &amp;amp; catalogue-driven sky-survey downloader</title>
    <link>https://community.wolfram.com/groups/-/m/t/3701280</link>
    <description>![Exploring NASA SkyView: live imagery, dark-nebula analysis, &amp;amp; catalogue-driven sky-survey downloader][1]&#xD;
&#xD;
&amp;amp;[Wolfram Notebook][2]&#xD;
&#xD;
&#xD;
  [1]: https://community.wolfram.com//c/portal/getImageAttachment?filename=ExploringNASASkyViewliveimagery.png&amp;amp;userId=20103&#xD;
  [2]: https://www.wolframcloud.com/obj/928898a9-67eb-4590-bdf7-0113b2c76db4</description>
    <dc:creator>Marco Thiel</dc:creator>
    <dc:date>2026-04-22T22:27:38Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3686348">
    <title>Formal symbols in the UD calculus: evaluation control</title>
    <link>https://community.wolfram.com/groups/-/m/t/3686348</link>
    <description>&amp;amp;[Wolfram Notebook][1]&#xD;
&#xD;
&#xD;
  [1]: https://www.wolframcloud.com/obj/e1aa2b28-96b1-4104-8347-1e38ecdf5e0d</description>
    <dc:creator>Brian Beckman</dc:creator>
    <dc:date>2026-04-14T16:21:26Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3673962">
    <title>View of the Moon from Artemis II: simulating the lunar flyby</title>
    <link>https://community.wolfram.com/groups/-/m/t/3673962</link>
    <description>![View of the Moon from Artemis II][1]&#xD;
&#xD;
&amp;amp;[Wolfram Notebook][2]&#xD;
&#xD;
&#xD;
  [1]: https://community.wolfram.com//c/portal/getImageAttachment?filename=ArtemisIIFlyBy_final.gif&amp;amp;userId=20103&#xD;
  [2]: https://www.wolframcloud.com/obj/54c0ec26-f350-4965-a1bc-bd7b5e34dbf5</description>
    <dc:creator>Jeffrey Bryant</dc:creator>
    <dc:date>2026-04-03T19:51:12Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3680003">
    <title>An efficient higher-order WKB code for quasinormal modes and greybody factors</title>
    <link>https://community.wolfram.com/groups/-/m/t/3680003</link>
    <description>&amp;amp;[Wolfram Notebook][1]&#xD;
&#xD;
&#xD;
  [1]: https://www.wolframcloud.com/obj/193a32aa-8598-4eb0-a601-ef448032e058</description>
    <dc:creator>Alexander Zhidenko</dc:creator>
    <dc:date>2026-04-09T10:35:12Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3672762">
    <title>Artemis II trajectory: crewed lunar flyby to launch on April 1, 2026</title>
    <link>https://community.wolfram.com/groups/-/m/t/3672762</link>
    <description>![Artemis II trajectory: crewed lunar flyby to launch on April 1, 2026][1]&#xD;
&#xD;
&amp;amp;[Wolfram Notebook][2]&#xD;
&#xD;
  [ORIGINAL GIF]: https://community.wolfram.com//c/portal/getImageAttachment?filename=10956ArtemisIItrajectorycrewedlunarflybytolaunchonApril1,2026.gif&amp;amp;userId=20103&#xD;
&#xD;
&#xD;
  [1]: https://community.wolfram.com//c/portal/getImageAttachment?filename=4398testing2-optimize.gif&amp;amp;userId=20103&#xD;
  [2]: https://www.wolframcloud.com/obj/1f4c613a-e72e-487b-9b5a-c75613d8a099</description>
    <dc:creator>Jeffrey Bryant</dc:creator>
    <dc:date>2026-03-31T21:27:57Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3672541">
    <title>WI2easy: warm inflation dynamics made easy</title>
    <link>https://community.wolfram.com/groups/-/m/t/3672541</link>
    <description>&amp;amp;[Wolfram Notebook][1]&#xD;
&#xD;
&#xD;
  [1]: https://www.wolframcloud.com/obj/7c20d0a3-0451-4f2c-95b5-d4014f395ab4</description>
    <dc:creator>Rudnei Ramos</dc:creator>
    <dc:date>2026-03-31T17:01:30Z</dc:date>
  </item>
  <item rdf:about="https://community.wolfram.com/groups/-/m/t/3671922">
    <title>Lie theory, featuring 3D rotations</title>
    <link>https://community.wolfram.com/groups/-/m/t/3671922</link>
    <description>&amp;amp;[Wolfram Notebook][1]&#xD;
&#xD;
&#xD;
  [1]: https://www.wolframcloud.com/obj/53dcf037-fe9d-4e60-a6b9-aaf92a854da6</description>
    <dc:creator>Brian Beckman</dc:creator>
    <dc:date>2026-03-30T15:51:29Z</dc:date>
  </item>
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