Brian MacGabhann.  “A History of Astronomy Part 2 – From Newton to Now”

SYNOPSIS:

This talk takes up the story of our understanding of the universe from where Newton left it off, by looking at what we still did not know; what are the stars? How do they shine?  How big is the Universe? Where did it all come from? The talk will look at how we slowly learned the answers to each of these questions, and thereby arrived at our present day understanding of the universe we live in. 

Bio:

Brian MacGabhann began amateur astronomy 45 years ago at the age of 14. He is the former education and outreach officer with Galway Astronomy Club, and later club chair. Founder and resident lecturer with the Renmore History Society in Galway. Has lectured extensively to clubs and groups throughout Ireland, including giving lectures at Dunsink Observatory, and the Kerry and Mayo Dark Sky festivals. 

OBSERVING A PARTIAL SOLAR ECLIPSE.

This eclipse starts at about 10.05, reaches its maximum of about 25% at 10.50, and ends at about 11.40. It will be noticeable from about 10.15 to about 11.30.

Firstly, you should NEVER look directly at the Sun with the naked eye (or specs!), and ESPECIALLY NOT with any sort of optical equipment such as telescopes or binoculars – to do so risks serious permanent eye damage.

But there are several ways to observe this event safely.

1. Pinhole projection. Make a pinhole or needle-hole in a piece of card, such as a piece of a cereal packet. Hold that up at right angles to the Sun and let it shine through the hole onto another piece of white card held a few inches behind it. You’ll see a round image of the Sun with a small ‘bite’ out of it, caused by the Moon passing in front of the Sun. Do NOT look at the Sun through the pinhole! The larger the hole, the brighter the image, but the fuzzier it will be. About 1mm diameter is probably best.

2. If you have a small refractor type telescope mounted on a tripod, keep the cap on the lens at the front, and on any finder telescope attached to it. Insert the lowest power / widest angle eyepiece you have (usually the one with the largest number in mm marked on it, e.g 25mm), remove any cap from the eyepiece, and position a piece of white card behind the eyepiece. Adjust the angle of the telescope so that its shadow on the card is smallest, which means it’s pointed roughly at the Sun. 

   If there’s a finder, remove the cap, but don’t look through it! Make fine adjustments to the pointing of the telescope until you see a small image of the Sun projected onto the card. 

  Then, or if there’s no finder telescope attached, remove the cap from the front of the telescope, and move it in fine adjustments until an image of the Sun appears projected onto the card. Put the cap back on the finder for safety. Then use the focus knob until that image is as sharp as possible.

   Remember, NEVER look through either the finder or the telescope while doing this.

   And don’t leave the telescope unattended, in case someone else tries to look through it.

3. If you have a pair of special eclipse glasses left over from previous solar events you can use them, provided there are no holes or scratches in them. To test them, look at the brightest light in your house through them – you should see absolutely nothing, except possibly the filament itself in a very bright (100W+) incandescent light bulb!

4. If you have access to the darkest grade of Welder’s glass (14), you can use that, but no other sorts of filters are safe.

Do NOT use 3D glasses, CDs, DVDs, mylar type film, e.g. from packaging or the interior of wine boxes etc. Not even multiple pairs of sunglasses are safe, as they may let through harmful UV radiation.

But if you can just barely see the Sun through thick fog or cloud, you can look at that for short periods, but if it starts to brighten so you can see it clearly, look away.

Further information and guidance can be found here https://www.space.com/15614-sun-observing-safety-tips-infographic.html 

“Planetary Nebulae and their role in the Cosmic Distance Ladder”, by Prof Marc Sarzi, AOP.

Details to follow

5th Oct: Prof Alan Fitzsimmons, QUB: “Moving an Asteroid – Did we do it?” (the results of the DART impact on Didymos)

Abstract:

On 27^th September at 00:14 BST, the NASA DART spacecraft hit the small asteroid moon Dimorphos at 6.1 km per second. Designed to change the orbit of Dimorphos around its parent asteroid Didymos, the collision was followed by the accompanying ASI spacecraft LICIACube and a multitude of Earth-based telescopes.

Two decades in the making, this was humanity’s first test of asteroid deflection technology, designed to prevent potentially catastrophic impacts on Earth in the future.

Did it work? What happened? This talk will briefly describe the background to the problem, and the mission plan for DART. First results from the encounter will be shown, and the talk will end with an overview of what happens next.