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Venus at dichotomy

Dominic Ford, Editor
From the Inner Planets feed

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The sky at

Venus will reach half phase in its 2016–2017 evening apparition. It will be shining brightly at mag -4.4.

From Cambridge , this apparition will be well placed and prominent, reaching a peak altitude of 40° above the horizon at sunset on 5 Feb 2017.

Begin typing the name of a town near to you, and then select the town from the list of options which appear below.

The table below lists how high Venus will appear at sunset over the course of the apparition. All times are given in Cambridge local time.

Date Sun
sets at
Venus
sets at
Altitude
at sunset
Direction
at sunset
07 Nov 201616:2818:3116°south-west
17 Nov 201616:1918:4417°south-west
27 Nov 201616:1219:0120°south
07 Dec 201616:1019:2223°south
17 Dec 201616:1119:4326°south
27 Dec 201616:1720:0430°south
06 Jan 201716:2520:2233°south-west
16 Jan 201716:3720:3737°south-west
26 Jan 201716:4920:4939°south-west
05 Feb 201717:0220:5440°south-west
15 Feb 201717:1520:5138°south-west
25 Feb 201717:2820:3634°west
07 Mar 201717:4020:0426°west
17 Mar 201718:5220:0814°west

A graph of the phase of Venus is available here.

Observing Venus

The 2016–2017 evening apparition of Venus
12 Jan 2017 – Venus at greatest elongation east
14 Jan 2017 – Venus at dichotomy
05 Feb 2017 – Venus reaches highest point in evening sky
18 Feb 2017 – Venus at greatest brightness

Venus's orbit lies closer to the Sun than the Earth's, meaning that it always appears close to the Sun and is lost in the Sun's glare much of the time.

It is observable for a few months each time it reaches greatest separation from the Sun – moments referred to as greatest elongation. These apparitions repeat roughly once every 1.6 years.

On these occasions, Venus is so bright and conspicuous that it becomes the third brightest object in the sky after the Sun and Moon. It is often called the morning star or the evening star.

Venus's phase

Venus's phase varies depending on its position relative to the Earth. When it passes between the Earth and Sun, for example, the side that is turned towards the Earth is entirely unilluminated, like a new moon.

Conversely, when it lies opposite to the Earth in its orbit, passing almost behind the Sun, it appears fully illuminated, like a full moon. However, at this time it is also at its most distant from the Earth, so it is actually fainter than at other times.

Venus shows an intermediate half phase – called dichotomy – at roughly the same moment that it appears furthest from the Sun, at greatest elongation. The exact times of the two events may differ by a few hours, only because Venus's orbit is not quite perfectly aligned with the ecliptic.

Venus's position

The coordinates of Venus when it reaches dichotomy will be:

Object Right Ascension Declination Constellation Angular Size
Venus 22h52m00s -07°34' Aquarius 24.9"
Sun 19h44m -21°14' Sagittarius 32'31"

The coordinates above are given in J2000.0.

The sky on 14 January 2017
Sunrise
07:10
Sunset
16:34
Twilight ends
18:14
Twilight begins
05:30

16-day old moon
Waning Gibbous

94%

16 days old

Planets
Rise Culm. Set
Mercury 05:31 10:11 14:51
Venus 09:23 14:59 20:35
Moon 19:35 01:26 08:23
Mars 09:43 15:29 21:15
Jupiter 23:52 05:31 11:07
Saturn 04:58 09:35 14:12
All times shown in EST.

Source

The circumstances of this event were computed using the DE405 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).

This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.

Related news

12 Jan 2017  –  Venus at greatest elongation east
05 Feb 2017  –  Venus reaches highest point in evening sky
03 Jun 2017  –  Venus at greatest elongation west
05 Aug 2017  –  Venus reaches highest point in morning sky

Image credit

None available.

Cambridge

Latitude:
Longitude:
Timezone:

42.38°N
71.11°W
EDT

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