Final evening observations of Venus

The 2024-2025 eastern elongation of Venus is now over as the planet reached inferior conjunction on the 23rd March and is now appearing in the morning sky. Before this happened I was able to make a few more observations of the planet as its phase shrank to a thin crescent. Firstly, I saw the planet on the 5th March 2025 in clear skies but relatively poor seeing. Venus was at an altitude of about 24 degrees in the West just after sunset. Here is the page from my notebook:-

I made the drawing using my 140mm Orion Maksutov-Cassegrain between 17:35 and 17:52 UT. The phase has shrunk considerably since my last drawing on the 25th January. From the drawing I estimated that the phase was 13% by measurement. This was slightly larger than the predicted phase of 11.2% predicted by the BAA. Notice also how the size of the planet has grown considerably from 29.6 arc seconds on the 25/1/25 to 51.5 arc seconds in this observation. 

On the 13th March at 18:16 UT I captured an image of Venus using my Tasco 18-36x spotting scope:-

 

This terrestial telescope has an aperture of about 50mm. This picture was taken at 36x and I used my Samsung phone to capture it. At this time the phase of Venus was about 5% and the planet was at an elongation of 19 degrees.

The final drawing I made of Venus was on the 17th March and by then the phase appeared to have shrunk to just 1%:-

Here I used my NexStar 102 SLT set up at the front of the house which is west facing. Venus was by this date not very far above the horizon after sunset (a mere 5 degrees in the west). The low altitude caused the seeing to be very poor but it made for a very beautiful sight. The crescent of the lit side was so thin that the atmosphere caused the image to flicker in different colours, like diamonds on a necklace. What's more, after careful observation, it was possible to see that the cusps of the crescent had extended further round the planet than would be expected for solid body with no atmosphere and I have tried to show this in my drawing. The cusps on such a body would be expected to end diametrically opposite each other where the terminator meets the edge of the planet. Instead the light carries on past this point causing appearance of the cusps to curve back on each other. I was very pleased to see that Paul Abel at the BAA produced a very similar drawing a day later.

By comparing what I could see at 73x with 5 phase diagrams ranging in phase from 1 to 5% in steps of 1% I estimated the phase to be 1% and this is smaller than the 3% predicted by the BAA. 

Finally, on the 18th March at 18:12 I captured my last image of Venus using my spotting scope at 36x again:-

 

 All text and images © Duncan Hale-Sutton 2025

Conjunction of the Moon, Venus and Mercury (and some geese!)

On the 2nd March, in the period of continued settled weather, we had a nice conjuction of the Moon, Venus and Mercury:-

 

This picture was taken at 18:14 UT about 20 minutes after sunset. The Moon is just 2 days old and a thin crescent. Venus is the bright object to the right of the Moon. The planet Mercury, which never strays very far from the Sun, can just about be made out to the lower right and just above some geese that happened to fly into my view! I used my Sony DSC-RX100 and an exposure of 1/40s, f/3.5 at ISO 1600. The equivalent SLR focal length was 58mm.

On this date Mercury was at an elongation of 16 degrees east and was magnitude -1.0 (compared to -4.8 for Venus). It reached greatest elongation on March 8th.

All text and images © Duncan Hale-Sutton 2025

Observation of Mars on the 1st March 2025

For the last week and a half we have had some very settled mild weather dominated by high pressure to the south of us. This has enabled me to leave my HEQ-5 telescope mount outside covered up with a plastic bag and to use it whenever I was able. Ten days ago on the 1st March I had another go at drawing Mars. This planet is now retreating from us and its diameter has shrunk from 13.6 arc seconds on the 2nd of February to 10.9 arc seconds on the 1st of March. As a consequence it is getting harder to make out the detail. Here is the page out of my notebook:-

At about eight in the evening Mars was quite high above the horizon and roughly due south. There was quite a bit of thin cloud/haze about but the seeing was pretty good and the image steady. I was using my Orion OMC140 Maksutov Cassegrain again with a 9mm orthoscopic eyepiece that gives a magnification of about 222x. I began with a pre-printed template and drew in the details using coloured pencils. The above image has washed out the original colours, so I have just reproduced the drawing below where I have adjusted the saturation and colour temperature:-

 

It seemed to me that the northern polar cap has either shrunk in size since my last observation or the cap has tilted away from us. To my eyes the southern cap area looked less dark than before and I actually thought frozen white parts were visible but this may not be the case. At this time the central-meridian longitude that was pointing towards us was 220 degrees. According to the Sky & Telescope Mars Profiler the dark area to the south is likely to be Mare Cimmerium. 

I have been in touch with the BAA Mars Section director Richard McKim to see if my drawings are of any use to the BAA but it seems I need to be able to resolve more detail before any science can be made from them. To this end I should really be using my x2 barlow lens as well to get the magnification up to 444x but I think I had been reluctant to do this because the image appears so much dimmer. The other alternative is to wait until another opposition in 2 years time when Mars will once again be a bit bigger (and brighter). Still, I have made a start! He did like the colours I was using which he said did match what he expected. I may try and do a disc drawing of Jupiter as further practice.

 All text and images © Duncan Hale-Sutton 2025