Urban Astronomy – Comet Leonard

Unmasked and Unafraid

Posted December 19, 2021

The night sky is pretty much a mystery to most City Dwellers.  The glare of city light drowns out all but the brightest stars – and planets don’t do much better.  If you are interested, I can tell you where to look to see these far-off worlds.  If you were not interested, you would have stopped reading after the first sentence. 

So, at this point, I know my audience. 

Comet 2021 A1 – Leonard

There is another “Eyes Only Visible” comet to be seen in the Southwestern sky, just after sunset. The current magnitude of Leonard is +4.6, so in the city, it is only just visible and would be better seen with binoculars.  Once again, do not use telescopes or binoculars to view the Sun – blindness will result!  I said “after sunset” so you should be OK if you listen to me. 😉

As is usual in these cases, the comet gets brighter not only because it gets close to the Earth.  It also gets brighter because it gets closer to the Sun.  The third brightening influence is the material that the closer sun vaporizes.  That stuff makes a cloud around the comet and is it also partially blown away by what is called the Solar Wind – in a comet’s tail.

Figure 1, above shows the location to view, which is conveniently close to Venus, which is the brightest thing in the sky.  If you can see the Planet, you should be able to see the comet – although you may need those binoculars to do so.  

We have had very cloudy weather here in Houston (today, Dec 19) is “Mostly Cloudy” at 4 PM, changing to “Cloudy” around Sunset at 5:26 PM.  Tommorow at Sundown the prediction is “Mostly Cloudy” and the comet will have moved slightly relative to Venus.  These next few days are literally the last chance to see Leonard, as it is on a hyperbolic orbit – which is a nerdy way to say that it will never return to the Solar System.  (Please see figure 2 below)

Figure 2. Comet Leonard is diving through the Solar System, never to return.

For readers not in the Houston area, just look for Venus (and Jupiter for orientation) and use the chart above to find the comet.  We are lucky to be able to have the two brightest objects in the sky (now that the moon is not around in the early evening) as our reference points.

Hasta Luego,


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s