Month: Dec 2024

Jupiter Problems

I normally stack lots of short exposures. Due to the limitations of my telescope, I need to spend a lot of time re-centering whatever I’m taking pictures of. This is OK for star clusters or galaxies or nebulae. I can spend hours collecting as many frames as I like. These objects barely change over a period of hundreds of years. So I did the same with Jupiter.

This picture was taken on 21 Dec at about 2 am. It’s a stack of about ten frames. It’s OK, but I thought I could improve it by stacking more exposures. But it seemed that the more frames I tried to stack, the worse the result became. What’s going wrong?

It took me ages to figure out the reason: Jupiter has changed! It may seem obvious, but the planet Jupiter rotates. In fact it rotates fast. Despite being large enough to swallow 1,000 earths, it’s day only lasts 10 hours.

This adds another complication when you’re trying to photograph it. For a planet that’s rotating fast it means I don’t have much time. Here’s the same picture on the right. This time contrasted with another, taken 20 mins earlier.

The planet does a full rotation of 360 degrees in 10 hours.
36 degrees in an hour.
12 degrees in 20 mins. 12 degrees is a huge amount.

Even in these low resolution, blurry images you can see that cloud features have moved significantly in 20 mins. Here’s the same comparison again. This time there’s a yellow rectangle highlighting a small collection of three greyish clouds against a brown background. The same three clouds are visible on the right hand image too but have clearly moved.

If only the planet would just stay still while I photograph it!

His Eminence Vincent Gerard Nichols, Cardinal Archbishop of Westminster, President of the Catholic Bishops’ Conference of England and Wales

Jesus was born in Bethlehem, by coincidence on Christmas Day. Forced there by the evil Romans, who did absolutely nothing for them. They were then forced to become refugees. It says it all, without contradiction, in the Big Book of Magic Stuff.

Even today, a small Catholic community persists in a region taken over by the wrong religion.

And there has been peace on Earth ever since. Especially in Bethlehem and the surrounding regions.

https://mega.nz/file/JnlkQTjI#0aVClx0kOG1c3On0uzfz3qWRXCyGYC4SNJNudYJ2MRI

Now actually Rev Jayne Manfredi

Even unbelievers give gifts at Christmas. But we Christians give to the poor. And we never tell anybody about it. We give to the homeless, the orphans, the elderly and bereaved. We never tell anyone about this either.

We do this because one third of the Invisible Magic Friend was born in a stable near the Winter Solstice. If he hadn’t been then we just wouldn’t bother with all that useless lot of hangers on.

https://mega.nz/file/Ejc2lSrQ#6r11jll2eOSasYD2btshBPMT0aRNW8j3rlHJxxqXjEU

Mare Crisium

The few clear nights recently have been dominated by a near full moon. You know what that means by now, more moon pics!

I’ve highlighted the Mare Crisium (“Sea of Crises” – who came up with these names?) on this full moon from the night of 15th Dec. It’s the dark patch on the top right of the red rectangle.

P1070719mareCrisiumRectSml

https://en.wikipedia.org/wiki/Mare_Crisium

I wouldn’t think close ups during a full moon would be that interesting. But a few days later, with the shadows beginning to grow on the surface, zooming in is a bit more fun. Here’s a close up of Mare Crisium from 17th Dec. I’ve tried to up the contrast a bit and bring out a bit of detail. Hopefully not too much. If you exaggerate the detail too much then the picture stops looking natural and it becomes very obvious that it’s been manipulated.

Fans of Star Trek: the Next Generation might be interested to know that one of the craters in Mare Crisium is named Picard. Not, it has to be said, after Jean Luc Picard, the captain of the Enterprise, but another Jean Picard, the 17th century French astronomer.

https://en.wikipedia.org/wiki/Jean_Picard

To give you a sense of scale. Picard crater is 23 km across. So about the size of a large town or city. The whole Mare Crisium is about 550 km across – roughly the size of England.

Three days later, on the morning of 20th Dec, Mare Crisium had disappeared into the shadows. The terminator between night and day had moved west. I’ve highlighted the area with the yellow rectangle.

The closeup from that night is centered on the large crater Theophilus between Mare Tranquillitatus to the north and Mare Nectaris to the south.

https://en.wikipedia.org/wiki/Theophilus_(crater)

None of these pictures are likely to win any prizes. But bear in mind they’re taken with a relatively cheap (by astronomy standards) 6″, entry level telescope, and a second hand mirrorless camera. Neither of which are designed for astrophotography. I’m still trying to see just how far I can push such modest equipment. I suspect the real limit is my location in the heavily light polluted Southend-on-Sea.

Any dark skies next week should be mostly moon free. So I have to start planning what to look at.

And if you managed to get this far, Happy Winter Solstice!

Rev Dr Rob Marshall, Priest at St John the Evangelist, Welwyn Garden City

What a remarkable coincidence that Jesus was born so close to the Winter Solstice and the arrival of more light.

I won’t spoil the surprise, but something wonderful is about to happen. The Temporarily Visible Third of the Invisible Magic Friend is about to be born in a stable in Bethlehem and save us all from the damnation that he so justifiably was going to inflict upon us.

Well, actually this definitely happened 2,000 years ago. So, shhhh. Until Christmas Day, don’t tell anybody.

https://mega.nz/file/E38zxTDT#oDJqP7sKcH1W0erFFWO89O5AvKM8SYr2Z0O7x0x8HOQ