Venus dazzles at dusk and closes in on Neptune – Astronomy Now Online

This looping animation depicts a southwesterly view one hour after sunset from 1331January 2020 at two-day intervals as seen from the heart of the UK. Dazzling magnitude-4.1 Venus passes just 4arcminutes (one-fifteenth of a degree) south of Neptune at 8pmGMT on Monday, 27January 2020, so both planets will fit in the same high-power telescope view from 6pmGMT until they set. Dont miss magnitude+4.2 naked-eye star Phi()Aquarii that lies within 0.9 east of magnitude+7.9 Neptune throughout the period. Note that the Moons apparent size on 27 and 29January is enlarged for clarity. AN animation by Ade Ashford.Even casual skywatchers cannot fail to notice brightest planet Venus currently hanging like a lantern above the southwest horizon at nautical dusk, which is presently about 6pmGMT for the centre of the British Isles. On 11January, Venus crossed the constellation border into Aquarius where it resides for the remainder of the month.

Neptune also currently lies in the constellation of Aquarius. Since the outermost planet shines at magnitude +7.9, its too faint to see with the naked eye, but it is a viable binocular target if you know where to look. Fortunately for skywatchers, Venus makes an increasingly convenient celestial signpost to Neptunes position as the gap between them closes throughout this month, culminating in a close conjunction on 27January 2020.Venus passes one-fifteenth of a degree south of Neptune at 8pmGMT at 27January 2020, but the pair will be very low in the UK sky. Observers in the British Isles are advised to look at 6pmGMT around the onset of nautical twilight when the two planets are about 19 high in the southwest. Their separation is slightly more than 7arcminutes at this time. In this simulated one-degree telescope field of view the magnification is 40-50. AN graphic by Ade Ashford.While there will no difficulty in identifying Venus in your telescope on the evening of 27January, Neptune may prove a little more difficult to see in the glare of its planetary sibling. Their difference amounts to a whopping 12 magnitudes, which is another way of saying that Venus is 63,000 times brighter than Neptune! If the outermost planet is lost in Venus dazzle, try to spot magnitude +4.2 star Phi()Aquarii in the same field of view shown above.

Venus narrowly misses PhiAquarii, passing just 56arcseconds south of the star at 05:20UT (5:20amGMT) on 28January. Sadly, this event will not be visible from Western Europe as the timing favours the North Pacific Ocean and the Hawaiian Islands. Neptune has its own close encounter with the star, passing just 2arcminutes north of PhiAquarii at 8:15pmGMT (20:15UT) on 10February 2020; observers in the UK can see the conjunction low in the west-southwest shortly after 6pmGMT that night.

Returning to this month, if you do succeed in viewing Venus and Neptune in the same telescope field of view, do bear in mind that their apparent proximity is merely a line of sight effect. On the evening of 27January, Venus lies a little more than 167million kilometres (or 1.117 astronomical units) from Earth, but outermost planet Neptune is a staggering 4,590million kilometres (or 30.683 astronomical units) distant.

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Venus dazzles at dusk and closes in on Neptune - Astronomy Now Online