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.
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.
|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