Saturday, 28 February 2009

Why Venus is so bright

For those who were interested in yesterday's photo of the crescent Moon and (crescent) Venus, this snapshot from Redshift 5 software shows why the planet is currently so bright.

From this angle, above the solar system, the planets are rotating round the Sun anti-clockwise. Because Venus is so close to us, it is visually much bigger than when on the other side of its orbit, even though only part of its cloudy 'surface' is illuminated.

However, Venus is going faster than us, as is Mercury (the swift 'Messenger of the Gods'), and will soon pass us on the 'inside track'. At that point, although it is closest to us, it will become much less visible as it gets nearer the Sun from our point of view.

By mid March it will be back to being the familiar 'evening star', visible just around sunset, particularly with evenings getting lighter.

By April, it will (if I've got this right) be re-appearing at a similar brightness, but this time as the 'morning star'. And with days getting longer there won't be many opportunities to observe it, so enjoy it while it lasts.

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