<story><title>Radar reveals two moons orbiting asteroid Florence</title><url>https://astronomynow.com/2017/09/05/radar-reveals-two-moons-orbiting-asteroid-florence/</url></story><parent_chain><item><author>jaquers</author><text>Is the &amp;#x27;light&amp;#x27; reflecting off the asteroid emitted from the sun? I had never seen or even knew radar could distinguish value like what is shown here.&lt;p&gt;I suppose terrestrial radar looks at much smaller objects and what it sees is emitted from the tower and bounced back in a straight line so that sort of makes sense.&lt;p&gt;More info on the observatory: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Goldstone_Solar_System_Radar&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Goldstone_Solar_System_Radar&lt;/a&gt;</text></item></parent_chain><comment><author>wiredfool</author><text>Here&amp;#x27;s a good explainer on what you&amp;#x27;re actually seeing in the radar image: &lt;a href=&quot;http:&amp;#x2F;&amp;#x2F;www.planetary.org&amp;#x2F;blogs&amp;#x2F;emily-lakdawalla&amp;#x2F;2011&amp;#x2F;3248.html&quot; rel=&quot;nofollow&quot;&gt;http:&amp;#x2F;&amp;#x2F;www.planetary.org&amp;#x2F;blogs&amp;#x2F;emily-lakdawalla&amp;#x2F;2011&amp;#x2F;3248.ht...&lt;/a&gt;&lt;p&gt;* The signal is emitted from a radar installation on the earth, and reflected back to another dish.&lt;p&gt;* Brightness is reflected signal strength. So surfaces that are perpendicular to us will reflect better. The less the surface normal points to us, the less reflection we see.&lt;p&gt;* Up&amp;#x2F;Down is Time axis. The points closer to us will return sooner than points farther away.&lt;p&gt;* Left&amp;#x2F;right is Doppler shift. Parts of the asteroid that are rotating away from us will show up on one side, parts rotating towards us will show up on the other side.&lt;p&gt;(this is the vertically oriented image).</text></comment>
<story><title>Radar reveals two moons orbiting asteroid Florence</title><url>https://astronomynow.com/2017/09/05/radar-reveals-two-moons-orbiting-asteroid-florence/</url></story><parent_chain><item><author>jaquers</author><text>Is the &amp;#x27;light&amp;#x27; reflecting off the asteroid emitted from the sun? I had never seen or even knew radar could distinguish value like what is shown here.&lt;p&gt;I suppose terrestrial radar looks at much smaller objects and what it sees is emitted from the tower and bounced back in a straight line so that sort of makes sense.&lt;p&gt;More info on the observatory: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Goldstone_Solar_System_Radar&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Goldstone_Solar_System_Radar&lt;/a&gt;</text></item></parent_chain><comment><author>db48x</author><text>No, that&amp;#x27;s not showing light reflected from the sun. In the still image, the radar source (aka Earth) is to the left; in the animation it&amp;#x27;s at the top.&lt;p&gt;In the still image, the vertical dimension is the bearing of the transmitted radar signal, while the horizontal dimension is distance away from Earth, as computed by the time of flight of the radar signals. In the animation those are swapped.</text></comment>