Tuesday 8 December 2015

Announcing: Toxic Tales and Animal Evolution!

The next meeting of Widnes SciBar will be as follows:-
 
7:30 pm on Wed 9th Dec in the Trafalgar Room at the Hillcrest Hotel, Cronton Lane,Widnes, WA8 9AR.
 
Please note that we recently changed to a different room - the Trafalgar room is on the first floor.
 
Kevin Arbuckle from the Department of Evolutionary Biology, Zoology and Ecology, University of Liverpool, will talk about:-
 
Telling Toxic Tales - Chemical Warfare in Animal Evolution.
 
Here is Kevin’s description of his talk:-
 
Kevin ArbuckleVenomous and poisonous animals inspire fear and fascination. Animals from across the ‘tree of life’ have used toxic and repellent chemicals to catch prey and avoid becoming a meal themselves. Not only do many of these species advertise their defence with beautiful colours but toxins may even shape the evolution of the animals that possess them. 

His University Home Page is here 



 

Bob Roach 30th November 2015.

The Asteroid Threat!

The Asteroid Threat

Widnes SciBar - 11th Nov 2015
 
Andy Newsam,  Professor of Astronomy Education and Engagement, Liverpool John Moores University.

Asteroids are small rocky objects orbiting the Sun. Although most asteroids in the Solar System are in the Asteroid belt between Mars and Jupiter, not all are restricted to it. Those not in the Belt could be a threat to Earth, as could those that are occasionally pulled out of that Belt by the gravity of Jupiter - these are called ‘Trogans’. As a result, there is a small possibility of one hitting the Earth but, if it did, the consequences could be massive. It is these ‘near Earth objects’ that astrophysicists are interested in. 

The craters peppering the Moon are a sign of how asteroids can come into the vicinity of the Earth - the age of these craters can be estimated from the amount of weathering that has taken place. There are far fewer known craters on the Earth but not all asteroid strikes will have left an identifiable crater - some will have landed in an ocean or vegetation may have obscured some craters on land.

An asteroid created the Barringer (or Meteor) Crater in Arizona about 50,000 years ago - the crater is about 1200 m across and 170 m deep. The asteroid was about 40 metres diameter - tiny as asteroids go. Such small asteroids are not yet detectable but that is not a great concern because the damage caused by them, whilst significant for many miles around, is not potentially
catastrophic for life on the Earth. 

Craters
In 2004 there was a ‘near miss’ when an asteroid of about 900 metres diameter passed between the Earth & Moon. If it had hit land on Earth it would have caused a crater about ‘the size of Wales’, throwing up a massive dust plume that would spread rapidly in the higher atmosphere and could block out sunlight and  so stop plant growth. Such an asteroid landing in an ocean would trigger a massive tsunami that would travel round the Earth. The Near Earth Asteroid Rendezvous (NEAR) space mission that landed on asteroid Eros in 2000 and the Rosetta Mission & its Philea probe landing on Comet 67P in 2014 have greatly increased the scientific understanding of asteroids. Previously, knowledge was limited largely to observing them from Earth and the evidence obtained from them hitting the Earth.

In brief, the risk of a large asteroid striking the Earth in our lifetime is small – they tend to occur about every 20 to 30 million years. However, the consequences of such a strike would be massive. Shown right is the Barringer Meteor/Crater in Arizona.
Andy described how scientists are seeking how to identify asteroids that pose a threat, how to track them and make them safe.

Detection. Most of the detecting work has now been done - it is believed that about 90% have been identified.

Liverpool Telescope, La Palma
Tracking. Tracking is currently the main focus of activity. It is being done by a combination of amateur observation (e.g. the privately run Spaceguard Centre in Mid-Wales) & large telescopes that are needed to track the smaller & more distant asteroids. Andy and his colleagues use Liverpool Telescope on the island of La Palma - it is the world’s largest fully robotic telescope, i.e. it can be operated from Liverpool. With such telescopes it is possible to pick out an asteroid from many stars by comparing images of the same area of sky taken some time apart - in contrast to the stars, an asteroid will have moved. Much of assessing is done by software but as it can only be relied upon to detect  95% of asteroids, the process isn’t perfect.

From these images, the course of an asteroid can be predicted for up to 100 years. If that suggests a danger to the Earth, the asteroid’s track will be kept under review - in time, a more accurate prediction of an asteroid’s risk can be made, often with a decision to remove it from the risk list.

As part of his ‘public engagement’ role, Andy spoke about involving children in identifying asteroids from two or more time-separated images from the Liverpool Telescope. A 12 year old spotted a faint trace that the professionals hadn’t noticed!

Making Safe. As yet we have no means of ‘making safe’ n asteroid heading our way. Use a nuclear bomb to blow them up? Apart from the practicalities of doing it, this could cause the Earth to be bombarded with broken lumps of the asteroid. Other possibilities include deflecting the asteroid’s path such as with the gravitational effect of a nearby massive weight (a ’gravity tractor) or painting one side white. If tracking identified a threat 20 years off, would there be the time & motivation to find a way to try to prevent a collision, to practice it & then to use it to make the Earth safe? 

Further Information

Andy is Director of the National Schools Observatory; ‘an online resource that brings the Universe  into the classroom’:- http://www.schoolsobservatory.org.uk/
Video of Andy actively engaging young people into science. Worth watching; Andy talks about finding asteroids from 42 minutes:- http://www.iop.org/resources/videos/education/schools-and-colleges-lecture/page_50047.html
Spaceguard Centre, Mid-Wales:- http://spaceguardcentre.com/

Bob Roach       30th Nov 2015