transit of Venus

I set my alarm clock for 4am and was disappointed to find a sky full of clouds that would prevent us from viewing the transit of Venus from Thurso and the surrounding area.

The BBC Horizon programme broadcast last night was very good.  You can still catch it on iPlayer for the next week or download it using the link below.

booklets for all standard grade physics units

I’ve been asked to post a link to all of the booklets so that people have access to something like the energy booklet as they revise using electricity and electronics.  I’ve added these to the standard grade page now.  Look for a link called whole unit notes in each section.

For those of you who have yet to download a copy of the SQA Physics booklet, get yours here.

how satellites rule our world

BBC2 showed a really good programme about satellites last night.  This screenshot showing a satellite passing over the Highlands is taken from about 17 minutes into the show.  Click on the picture to visit the BBC’s own page about the documentary.

It was quite eye-opening to see just how much modern society relies on satellite technology.

ray diagram revision

We’ve reached the Space unit and are almost at the end of the course.  I showed you how to draw ray diagrams when we looked at lenses during the Health Physics unit.  Some people have asked me to repost these video clips as they were not sure how to draw ray diagrams for our telescope this morning.

Watch these clips and make sure you know the six terms we use to describe the image formed by a lens. You should be able to select three words to describe the image in your ray diagram.

The second video looks at a ray diagram when the object is less than one focal length away from the lens.

Once the ray diagram is complete, we need to describe the image that has been formed.  The description must tell us about the size, orientation and type of image that is formed.

Size
If the image is larger then the original object, we say the image is magnified
If the image is smaller than the original object, we say the image is diminished.

Orientation
If the image is the same way up as the object, we describe it is upright.
If the image is upside down compared to the object, we describe it as inverted.

Type
If the object and image are on opposite sides of the lens, it is a real image.
If the object and image are on the same side of the lens, it is a virtual image.

very large telescope

I found a brilliant timelapse video on the Popular Science site.  It shows the Very Large Telescope (VLT) at work in Chile.

Here are some VLT links to explore

You can get a pdf summary of the VLT from the European Southern Observatory (ESO), the organisation that runs the VLT, by clicking on the download link below.

Endeavour takes antimatter hunter to the space station

`image by NASA`

A few weeks ago we were all ready to look up for an evening sighting of the space shuttle Endeavour as it separated from its external fuel tank while passing over the UK.  That launch was delayed but NASA is set to try again today.

Endeavour is the newest vehicle in the shuttle fleet.  It was built as a replacement for Challenger.  This will be Endeavour’s last mission and its task is to carry the Alpha Magnetic Spectrometer (AMS-02) up to the International Space Station.

Launch is scheduled for 1.56pm UK time and you can watch it live on NASA TV.  Alternatively, you can watch the launch as a webcast from CERN, starting at 1.45pm.

AMS is designed to search for antimatter, a substance first proposed by British Physicist Paul Dirac.

Physicists believe that there should be a balance between matter and antimatter .  The problem is that we live in a universe that seems to be made from matter, not matter and antimatter, so the question is…

Particle physicists at CERN’s Large Hadron Collider have an experiment that is looking for an answer to this question.  The particle physics research teams at CERN were given the job of building the AMS, which was transferred to the Kennedy Space Centre earlier this year.

The videos below are from CERN’s multimedia library for the AMS project and will give you an idea of the role of AMS.  The first film is less than one minute long and designed to act as a trailer for the project.  The second is longer (15 minutes) and has several interviews with key project staff.

re-entering the earth’s atmosphere

In space there is no air resistance to oppose motion, so the Space Shuttle orbiter can travel at very high speeds, up to 17,321 mph!  At these speeds, the orbiter experiences enormous air resistance as it descends into the Earth’s atmosphere at the end of its mission.

This air resistance is just like any other form of friction – it converts kinetic energy into heat energy.  The effect of this heat energy is demonstrated in this video clip taken by a Canadian police car camera.  It shows a meteorite burning up in the atmosphere above Edmonton.

Thankfully most meteorites do burn up in the atmosphere, although the dinosaurs were not so lucky.

The high temperatures created during re-entry ionise the gas around the orbiter and this is often seen as a bright light in NASA cockpit videos, such as the one shown below.

To protect the vehicle and its crew from these high temperatures, the underside of the orbiter is covered by a layer of heat resistant tiles called the thermal protection system.  This NASA clip explains how the tiles are constructed and arranged on the underside of the orbiter.

When Columbia was launched in 2003, something fell against the insulation on the left wing and knocked off some of the tiles.  This hole in the thermal protection system caused Columbia to explode over the US as it re-entered the atmosphere.  There is a wikipedia article about the Columbia disaster.

Video footage of NASA’s Houston control room from the morning of the disaster was included in the BBC Horizon documentary Final Descent – Last Flight of Space Shuttle Columbia.

WARNING: This last film is an excerpt from the Horizon programme and includes genuine cockpit video that was found in the wreckage, with some clips of the crew’s final minutes before they were killed.

There is a good description of the Space Shuttle at How Stuff Works.

star classification

We know that our sun is a fairly common star.  In fact, the fanciest thing about our sun is probably the fact that the 3rd planet (Earth) in its solar system has life!

In this video, astronomers talk about how they can use the line spectra from stars to classify them into different categories.

what is a parsec?

Someone asked about parsecs when we spoke about the light year earlier in the week. Here is the video about parsecs that I promised.

4.3 – How to draw ray diagrams

I set you a task at the start of the week.  You were asked to complete a ray diagram at home and use 3 words to describe the image that was formed.

Here are 2 short videos to remind you how to draw a ray diagram.  The first video is an introduction to ray diagrams.

The second video looks at a ray diagram when the object is less than one focal length away from the lens.

Once the ray diagram is complete, we need to describe the image that has been formed.  The description must tell us about the size, orientation and type of image that is formed.

Size
If the image is larger then the original object, we say the image is magnified
If the image is smaller than the original object, we say the image is diminished.

Orientation
If the image is the same way up as the object, we describe it is upright.
If the image is upside down compared to the object, we describe it as inverted.

Type
If the object and image are on opposite sides of the lens, it is a real image.
If the object and image are on the same side of the lens, it is a virtual image.