NASA studies the Van Allen belts

NASA has recently sent up 20 huge balloons to investigate charged particles that are lost from the Van Allen belts.

For GCSE Astronomy you need to know what the Van Allen belts are!

There are 2 belts around the Earth containing charged particles and both were discovered by James Van Allen.

The inner belt consists of protons and electrons, while the outer belt just consists of high energy electrons.

The only time manned missions have travelled through the Van Allen belts is for the Moon studying Apollo Missions running from 1961 to 1972. The highlight being in 1969 when man finally set foot on the moon.

The belts were thought of as a major hazard  for the astronauts due to the high levels of radiation. Fortunately they passed through the belts in such a short period of time that exposure levels were very low.

Most of the particles in the belts are captured in our magnetic field from the solar wind.

Other particles that are not captured may get attracted to the poles and can then pass through our atmosphere creating the northern lights (aurora borealis) and southern lights (aurora australis).

The high energy particles ejected from the Sun's upper atmosphere are referred to as 'solar wind'.

Solar Flares are often responsible for large ejections. A particularly large solar flare from 2012 is pictured below.

The BARREL (Balloon Array for Radiation-belt Relativistic Electron Losses) mission is trying to find out what happens to the charged particles that are ejected from the Van Allen belts.

Scientists want to gain a better understanding of the belt so they can protect their satellites and space equipment better.

'Red Rose' Storm found on Saturn

In 2004 the Cassini Space Probe reached Saturn. It is still in orbit there and recently sent back this stunning image of an enormous hurricane at the planet's north pole thought to be 1000 miles wide.

Saturn is the second largest planet in our Solar System and is best known for its ring systems.
All of the four outer planets (the gas giants) have ring systems but Saturn's icy systems reflect huge amounts of light making them easier to see.

 

 The above piture was taken by Cassini as it was in Saturn's shadow and looked back towards the eclipsed Sun. Saturn is still visible due to reflected light off the rings.
The dulling of Saturn made the rings much more visible and even led to the discovery of new ring systems.
Saturn has a total of 8 ring systems of which most are visible below. This includes 3 main rings and 5 dusty rings. The gap between Satturn's A ring and B ring is known as the 'Cassini Division'.

 

Earth, Moon & Sun

End of Topic Review

During the first term we have managed to cover the first of four topics in the GCSE Astronomy course.

Next term we will study 'Planetary Systems'. In this unit we will cover our Solar Sytem, Comets, Meteors and how we search for planets outsuide of our Solar System.
This is a good time to fill in any gaps in your knowledge.

Click here to see the full breakdown of everything you need to know from the Earth, Moon & Sun topic. Read pages 11 to 14.

Would you be able to write about the following?
This should give you a good idea on how you are following the course so far.

• The most important features of the Earth?
• The electomagnetic spectrum and the issues with observing each part of the spectrum with relation to the atmosphere.
• Why is the sky blue?
• What is light pollution?
• Eratostene's calculation of the Earth's circumference.
• What is the difference betweeen a Solar day and a Sidereal day?
• Refracting and Reflecting Telescopes.
• The Van Allen Belts
• The Moon's main features
• What are the Maria and Highlands and what caused the Maria.
• The far side and near side of the Moon and the differences between them.
• Rilles and Wrinkle Ridges.
• ALSEPS.
• Giant Impact Hypothesis.
• How to observe the Sun safely.
• What are Sunspots, including a labelled diagram and what causes them.
• Different rotational periods of the Sun.
• Using Sunspots to calculate the Sun's rotational period.
• The Solar cycle and butterfly diagrams.
• Nuclear Fusion as the source of the Sun's energy.
• Solar Prominences, Solar Flares, Solar wind and the Aurora.
• Solar and Lunar eclipses.
• Lunar phases.
• Shadow sticks and sundials.
• The equation of time.

Don't worry about memorising all the big numbers yet. We'll get those sorted closer to the exam.

For help you could;

• Read your text book.
• Read your notes.
• Ask for help from Mr.Williams during break, lunch or after school.
• Visit this excellent GCSE Astronomy revision website.

Sir Patrick Moore

1923 - 2012

Patrick Moore had presented 'The Sky at Night' since 1957 up until last month.
He has inspired a generation of Astronomers.
Below are some clips from the show and some pictures from Patrick's career.



 

How Eratosthenes measured the circumference of the Earth

Eratosthenes was an interesting character

He was a mathematician who lived in the 3^rd century BC who did some very important work.

He gets a mention on this course for his brilliant measurement of the Earth’s circumference.

Despite all his great work in many fields his nickname was ‘Beta’ as he tended to be second best in a number of disciplines.

Eratosthenes lived in Alexandria in Egypt but was born in Syene (now Aswan) and it was these two places that he used in his calculation.

 

Syene lies on the Tropic of Cancer.

On June 21^st (midsummer’s day) on the Tropic of Cancer, the sun is directly overhead (at our Zenith) at noon.

Any vertical object would have no shadow.

He was in Alexandria though, which is about 800 km North.

He measured the angle of the Sun here by looking at the shadow of a vertical object and calculated that this angle must be the same angle between Syene and Alexandria from the centre of the Earth.
 

See diagram below.

 

This showed that there is 7 degrees between Syene and Alexandria.

You need about 50 lots of 7 degrees to make a full circle so you must need about 50 lots of the distance from Syene to Alexandria to get around the world.

He calculated the Earth’s circumference to be about 40,000 km, which was pretty much spot on!

If you are able to understand this, you should do very well on the course.

A* and A grade students will be able to explain how Eratosthenes did his calculation with the use of a diagram.

Using the National School's Observatory (NSO)

It is now easy to get your own images of the Universe using a professional telescope
You won't need to buy any equipment and you can do it from the comfort of your computer.

You just need to get a log in for the National School's Observatory (NSO) off Mr Williams.

It's free and it allows you to request the Liverpool John Moores University telescope, located in sunny Tenerife high up on a mountain, to take an image of a point of interest of your choosing in the night sky.

The special thing about this is that they are YOUR images.
The University got funding for the project by giving up time on their telescope to schools like ours so your image will be unique.

You can use it to get images of the Planets, Craters on the Moon, Nebulae, Galaxies or even search for asteroids.
Below are some examples of 3 colour images produced by our Astronomy class of 2012 as part of their coursework.

                

M57 (The Ring Nebula) by Lottie Aitken                                                                 NGC 6946 by Emma Irving

                     

M27 (Dumbell Nebula) by Mark Hogan                                                 M76 (Little dumbell nebula) by Oriana Gibson

Just get logged in, click on 'Go Observing' and follow the instructions.
You may have to wait a few days for the telescope to get round to taking your image.
Once you have your obesrvations you will need to download and use LT image to view them.
This page explains it all.

Enjoy!