Mars & Uranus


Mars and Uranus conjunctions occur every two years as the two planets pass by each other. This years close conjunction event was a separation of 1.5° on 21st January. My image was taken two days later, when the separation between the two had widened to slightly over 2°.

Planetary conjunctions of one kind or another occur every year. It’s only a month since we had Jupiter & Saturn in conjunction, with Mercury joining them near the horizon a couple of weeks later. Why are conjunctions common? The short answer is that the planets all follow a similar path across the sky, called the ecliptic – and as they all travel at different speeds, the faster planets overtake the slower ones as seen from Earth.

The Solar System
Image: Wikipedia

Uranus is only dimly visible in binoculars with a magnitude of +5.8, whilst Mars still shines prominently in the West with a magnitude of +0.3, (fourteen times brighter than Uranus).

The scale of the Solar System is demonstrated by the time that light took to reach us at lightspeed 300,000 km/s. From Mars it took only nine minutes. From Uranus it took 164 minutes to reach my camera.

It was nice to be outside under the stars on a balmy 25°C evening.

Image Data

Feature image date:2021-01-23
Field of View:15° x 10°
Exposure:4 sec, f/2, ISO 400
Camera:Canon 60D, 135mm lens

Images © Roger Powell

I’m a founder member of Macarthur Astronomical Society


  1. Nice “capture!” Good to hear your getting same clear skies again. oh, and it’s just 25 Deg here too, this evening… F , that is :-(. M 🙂


  2. Your nice view matches what I saw on the same night. Mars was easy to spot. Uranus was tiny, but had a bit of a disc unlike those few neighboring stars.

    Imagine how cold 25 Kelvin would be.


    1. I was disappointed the two didn’t get a bit closer so I could capture them in the telescope.

      25º would be inconceivably cool. I think any exposed bits might crack and fall off….

      Liked by 1 person

    1. Thanks. I followed the link. That was an innovative exercise and brilliant video imaging.

      We have a permanent scale model here in NSW on approach to the Siding Spring Observatory. To drive to the observatory you pass by a model of each planet at a distance of many kilometres.

      The AAT telescope dome represents the Sun. Mercury is 1.2 kilometres from the dome and Pluto is 190 km away.

      Liked by 1 person

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