Planet Venus graces the west-southwest horizon of UK skies at dusk, attaining its greatest brilliancy of magnitude -4.8 on 17February. To put this in context, Venus is now in excess of twenty times more luminous than brightest star Sirius currently low in the southeast. Planet Mars, magnitude +1.2, lies just 7degrees (the field of view of a 7x binocular) to Venus upper left. Gas giant planet Uranus also lies close by. AN graphic by Ade Ashford.Currently setting over four hours after the Sun as seen from the heart of the British Isles and visible in the west-southwest at dusk, dazzling Venus is about to hit peak brightness in the constellation of Pisces. The planet attains magnitude -4.8 on Friday 17February, some 21 times the luminosity of Sirius the brightest star gracing the southeast horizon as darkness falls.

At UK dusk on 17February, Venus lies 0.42 astronomical units (AU), or 39million miles (63million kilometres) from Earth. It has a 39.4-arcsecond-wide, 27percent illuminated crescent that requires a telescope magnification of just 48x to make it appear the same size as an average Moon to the unaided eye. As the days pass, Venus phase decreases and its apparent size increases as the planets orbital motion carries it further around the Sun and nearer the Earth.

Planet Mars lies less than a span of a fist at arms length to the upper left of Venus until about the third week of the month, so it is easy to identify. On the night of Venus peak brightness the Red Planet shines at just magnitude +1.2, making it a full six magnitudes or 250 times fainter than its dazzling sibling. In a telescope, Mars disc is a tiny 4.8arcseconds wide one-eighth that of Venus on account of a distance of 1.96AU or 182million miles (294million kilometres).

To complete the evening planet ensemble, you may wish to seek out Uranus. The magnitude +5.9 gas giant lies 6.2degrees (or slightly less than a 7x binocular field of view) to Mars upper left. Some 3.4arcseconds in size, Uranus lies 20.52 astronomical units or 1,908million miles (3,070million kilometres) from Earth on 17February.

Can Venus cast a shadow? Returning to the brightest planet, there is a fun experiment that you might like to conduct if you live in (or have access to) an area where there is no light pollution especially now that the Moon is rising after 8pm. Using our Almanac, select the city nearest you and note the time at which astronomical twilight ends for the centre of the British Isles, this is currently about 7:20pmGMT.

Allowing at least 15minutes for your eyes to become dark adapted, turn your back to Venus close to the time astronomical twilight ends and see if you can discern your shadow cast solely by the light of Venus on a west-facing fence or wall. You may need to use your peripheral vision to see it. While Venus remains visible until 9pm for much of the UK, you need to conduct this little experiment with Venus highest in the sky as soon as darkness falls.

I have twice seen my shadow cast by the light of Venus while working at the Mount John University Observatory under the pristine, exceptionally dark skies found at the heart of New Zealands South Island.

For a comprehensive guide to observing all that is happening in the coming months sky, tailored to Western Europe and North America, obtain a copy of the February 2017 edition of Astronomy Now.

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See planet Venus hit peak brightness in the evening sky - Astronomy Now Online