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International Space Station

Some amazing pictures of the I.S.S. from John Arnold's back garden in Leeds.

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Information...

The International Space Station (ISS) is the ninth manned space station, and is a multinational collaborative project by Russia, the US, Japan, Europe and Canada.

Constructed in a modular fashion, the first component was launched into space in 1998, and it has been occupied continuously aince 2000.

The station is now the largest artificial object in space. It orbits the Earth about every 94 minutes and is in a low-Earth orbit of 400 kilometres. Many scientific experiments have been conducted on the station with its micro-gravity space environment. The station also serves as a testing ground for further space exploration, and provides information on the long-term effects on the human body from prolonged periods in space.

The station is divided into two sections. The Russian Orbital Segment (ROS) which is operated by Russia, and the United States Orbital Segment (USOS) which is shared by many nations.

For more information on the ISS see NASA's webpage and the station's Wikipedia entry.

 

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Apparent Magnitude

The apparent magnitude of a star is a measure of how bright it appears from Earth. The scale was introduced over 2,000 years ago by the Greek astronomer Hipparchus, who grouped stars into six categories. The brightest 20 or so were deemed to be 'first magnitude', slightly dimmer stars 'second magnitude', and so on until the barely visible stars were classed as 'sixth magnitude'.

Later it was recognised that our eyesight, once it has been given time to get used to darkness, has a logarithmic response. i.e. a Mag. 1 star is actually 2.512 times brighter than a Mag. 2 star, or 6.310 times brighter than a Mag. 3 star (2.512 x 2.512 = 6.310).

The six Magnitudes thus corresponds to a 2.5126 difference in brightness or 100x.

Apparent magnitude

Today the scale has now been extended, so that brighter objects can have an apparent magnitude of 0 or even negative. The brightest star Sirius, for example, has an apparent magnitude of -1.44 and the Sun is a whopping -26.74, due to it's close proximity to Earth.

 

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