© NASA/Ricardo Nunes

Venus at dichotomy

Dominic Ford, Editor
From the Inner Planets feed

Objects: Venus
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The sky at

Venus will reach half phase in its 2018–2019 morning apparition. It will be shining brightly at mag -4.4.

From Fairfield , this apparition will not be one of the most prominent but prominent, reaching a peak altitude of 33° above the horizon at sunrise on 14 Dec 2018.

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 sunrise over the course of the apparition. All times are given in Fairfield local time.

Date Sun
rises at
rises at
at sunrise
at sunrise
04 Nov 201806:3005:2411°south-east
14 Nov 201806:4204:2622°south-east
24 Nov 201806:5403:5029°south-east
04 Dec 201807:0503:3132°south-east
14 Dec 201807:1303:2533°south-east
24 Dec 201807:1903:2832°south-east
03 Jan 201907:2103:3630°south-east
13 Jan 201907:1903:4727°south-east
23 Jan 201907:1404:0025°south-east
02 Feb 201907:0504:1322°south-east
12 Feb 201906:5404:2420°south-east
22 Feb 201906:4004:3118°south-east
04 Mar 201906:2504:3516°south-east

A graph of the phase of Venus is available here.

Observing Venus

The 2018–2019 morning apparition of Venus
26 Oct 2018 – Venus at inferior solar conjunction
29 Nov 2018 – Venus at greatest brightness
14 Dec 2018 – Venus reaches highest point in morning sky
05 Jan 2019 – Venus at dichotomy
06 Jan 2019 – Venus at greatest elongation west

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 15h46m20s -16°21' Libra 24.9"
Sun 19h04m -22°36' Sagittarius 32'31"

The coordinates above are given in J2000.0.

The sky on 05 January 2019
Twilight ends
Twilight begins

29-day old moon
Waning Crescent


29 days old

Rise Culm. Set
Mercury 06:24 10:56 15:29
Venus 03:36 08:40 13:44
Moon 06:57 11:40 16:22
Mars 10:58 17:04 23:11
Jupiter 04:56 09:38 14:21
Saturn 07:06 11:44 16:23
All times shown in EST.


The circumstances of this event were computed using the DE430 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

05 Jan 2019  –  Venus at dichotomy
06 Jan 2019  –  Venus at greatest elongation west
17 Apr 2019  –  Venus at aphelion
08 Aug 2019  –  Venus at perihelion

Image credit

© NASA/Ricardo Nunes






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