Seeing Saturn

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Digital sketch…

Years ago I had the pleasure of using a low powered telescope. I managed to find Juiter and then further away in the darkness was Saturn. It was amazing, the Rings were tipped up so they were much more visible than when they are in the a more horizontal plain. It was tiny, so small, but I could see it wavering slightly in the night air. I think Galileo thought it looked like it had ears?

To see planets with your own eyes, however small they appear is wonderful. The time it takes for the light to get to us means you scan look into the past. So it’s almost like time travel too!

If you ever get the chance, look up and see the sky….

In other news..

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Digital illustration of a comet. Didn’t want to use someone else’s copyright photo. This is just to give an impression of its colour….

I get alerts from Spaceweather.com about all sorts of astronomical events. I got this alert about a comet this morning. As we are in ‘interesting times’ I thought I would let you know.

Here is a short excerpt with the link:
COMET ATLAS IS BRIGHTENING FASTER THAN EXPECTED: Get ready for a wild ride. Comet ATLAS (C2019 Y4) is plunging toward the sun and, if it doesn’t fly apart first, it could become one of the brightest comets in years. Amateur astronomers are already getting fantastic images as the comet brightens even faster than expected. Visit Spaceweather.com for the full story.

I don’t think the link will work from here, but it’s an easy address to find.

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World

_20200303_224853what would happen if the Earth was tipped up on its axis?

The world would spin so the equator was spinning at nintey degrees or so to where it is now. Every twenty four hours it would still spin West to East as it does now, but the Sun would not rise and set every day. I think it would only do that when the Earth was mid way between when either pole faced the Sun. Because the Earth rotates round the Sun. So the North or North East or North West would face the Sun for half  of the year and the South, South East and South West for the other half.

So what would happen to the poles? Even now, because the Earth is tipped at an angle and doesn’t rotate vertically, we get summers and winters. So there  twenty four hour days in the polar summer, and twenty four hour nights in polar winter. If the Earth was tipped over more the twenty four hour days and nights would last for months. The side away from the Sun would be colder, the side towards it would be hotter. Perhaps all the ice would melt at one pole and freeze much more at the other? Who knows? I’m sure scientists would have the answer. Thankfully we don’t face that question. Sadly we do face climate crisis. We need to sort out the current situation. How? I don’t know the answer to that. But perhaps we should follow what teachers put on school reports. We must try harder?!

How to tell the earth is a sphere…

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So how can you tell the Earth is a sphere? The ancient Greeks worked it out ( I don’t remember the name of the person who did).

The experiment was to put a stick in the sand at or near the equator, so it would have a tiny shadow directly underneath the it at mid day as the Sun was directly overhead.

If you place a stick upright, at 90° to the Eaths surface either North or South of the equator, the stick casts a shadow at mid day. (Look at the hands of a clock the hands move round in the same way). Say the equator is 3pm and the Sun is overhead, you would get no shadow, then as you go further away from the stick at the equator you get increasing angles (see diagram). Eventually at the poles the shadows would be at their longest.

So how can you tell its a sphere? The angles add up. You can calculate the curvature of the planet from these simple experiments. The ancient Greeks got very close to calculating the circumference of the Earth. Their calculations were only a small percentage out on their measurement.

 

Tee design

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Day 17 of the challenge on Facebook, today it was an ethical tee shirt design. I said I would like the world to concentrate on finding peace, and supporting nature by cleaning up the environment and taking the climate crisis seriously. I did think of adding flames but that seemed too much. My only concern is the tee shirts would have to be ethically sourced, carbon neutral and any workers paid a living wage. Too much to hope for?

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Last decade had highest ever recorded temperatures.

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Three maps, dated 1970-74, 1997-2001, 2015-19. There were others but I didn’t snap them in time. So we are getting hotter. Life will change, and possibly catastrophically if we don’t do something. I remember doing a collage about population growth in the 1970’s. I did a picture of earth with a line of people snaking away from it towards the moon. I’ve always been conscious of the environment. I was a tree warden in about 1975 and told people off for damaging trees. I think I got carried away once and really told some boys off about their behaviour. Fast forward several decades, and things are only getting worse. X

Annular Eclipse

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There was an eclipse today in some parts of the world. Not here though. This was an annular eclipse, where the moon doesn’t fully cover the sun and leaves a ring of sun shining behind the moon.

So why does this happen. In normal eclipses the moon appears to be the same size as the sun so its completely covered. That is because the moon is something like 40 times smaller than the sun, but also 40 times closer to us. So they have the same apparent size in the sky. But with an annular eclipse the Sun can be slightly closer or the moon slightly father away. Why? Because the Earth rotates round the Sun in an ellipse, which is an oval with two focal points. The sun sits on one focus, but the Earth orbits around both. That means sometimes it is further away from the sun and sometimes closer Then it also means the moon is further away from the sun or slightly closer to it. The moon rotates round the earth in the same way in an elliptical orbit. So sometimes it is closer to, and sometimes further away. If you add the two positions up further to the sun and further away from the earth you get an annular eclipse.

I can’t explain it more clearly. It is most difficult to think your way through how it works but I hope this makes sense.