# Historic Event in Astronomy

Today, Friday 15th February 2013.  Russia’s Ural mountains.  A fireball streaks through the clear morning sky.  Loud bangs follow.  A meteor crashes in Russia about 1,500 kilometres (930 miles) east of Moscow.   Continue reading Meteors over Russia

# Rainbows: Technicolor Symphonies in the Sky

Rainbows are one of Nature’s most gorgeous optical spectacles to behold, brightening up clouded skies with an ephemeral palette of colours when the light falls just right…  Continue reading Rainbows, Rainbows Everywhere!

# Earth’s Electric Field

The Earth has an electric field.  On average, this field points vertically downwards and it has a magnitude of about 100 N C-1 (Newtons per Coulomb).  It exists because the Earth’s surface carries a negative charge of – 5 x 10C, while the upper atmosphere carries a compensating positive charge.  An average of 400,000 thunderstorms a day  Continue reading Lightning and the Earth’s Electric Field

# Black Holes

Black holes are known to exist at the centres of most galaxies, including our own Milky Way.  The masses of those black holes are correlated to many of the properties of their host galaxies, which strongly suggests that galaxies and black holes evolve together.  Measuring their masses Continue reading How to Weigh a Supermassive Black Hole?

# Record-Breaking Space Dive

14th October 2012.  During his ultimate high-altitude parachute jump, Felix Baumgartner spends approximately 4 minutes and 22 seconds in freefall, at the maximum speed of 1,342 kilometres per hour.  Continue reading Fallen from Outer Space…

# Fiat Lux…

Light.  Most of us take it for granted during the day.  And at night, we have learned to domesticate it.  Light, the natural agent that stimulates our sense of sight and makes things around us visible.  Continue reading Let There Be Light…

# Physical Constants (SI Units)

Avogadro Constant $N_{A} = 6.022 \times 10^{23} mol^{-1}$

Bohr Radius $a_0 = 5.29 \times 10^{-11} m$

Boltzmann Constant $k = 1.381 \times 10^{-23} JK^{-1}$

Charge on an Electron $e = - 1.602 \times 10^{-19} C$

Gravitational Constant $G = 6.673 \times 10^{-11} Nm^{2} kg^{-2}$

Magnitude of Acceleration due to Gravity $g = 9.81 m s^{-2}$

Permeability of Free Space $\mu_{0} = 4 \pi \times 10^{-7} T m A^{-1}$

Permittivity of Free Space $\epsilon_{0} = 8.854 \times 10^{-12} C^{2} N^{-1} m^{-2}$

Speed of Light in a vacuum $c = 2.998 \times 10^{8} m s^{-1}$