© NASA/Ricardo Nunes

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 2017 morning apparition. It will be shining brightly at mag -4.3.

From Cambridge , this apparition will not be one of the most prominent but prominent, reaching a peak altitude of 30° above the horizon at sunrise on 26 Jul 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 sunrise over the course of the apparition. All times are given in Cambridge local time.

Date Sun
sets at
Venus
rises at
Altitude
at sunrise
Direction
at sunrise
07 May 201705:3203:4818°north-west
17 May 201705:2203:3119°north-west
27 May 201705:1403:1520°north-west
06 Jun 201705:0903:0122°north-west
16 Jun 201705:0802:4924°north-west
26 Jun 201705:1102:3926°north
06 Jul 201705:1602:3328°north-west
16 Jul 201705:2402:3029°north-west
26 Jul 201705:3302:3330°north-west
05 Aug 201705:4302:4030°north-west
15 Aug 201705:5302:5330°north-west
25 Aug 201706:0403:1129°north-west
04 Sep 201706:1403:3128°north-west
14 Sep 201706:2503:5426°north-west
24 Sep 201706:3604:1724°north-west
04 Oct 201706:4704:4122°west
14 Oct 201706:5805:0519°west
24 Oct 201707:1005:2917°west

A graph of the phase of Venus is available here.

Observing Venus

The 2017 morning apparition of Venus
25 Mar 2017 – Venus at inferior solar conjunction
26 Apr 2017 – Venus at greatest brightness
03 Jun 2017 – Venus at greatest elongation west
04 Jun 2017 – Venus at dichotomy
05 Aug 2017 – Venus reaches highest point in morning sky

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 01h46m20s +08°31' Pisces 23.6"
Sun 04h48m +22°25' Taurus 31'31"

The coordinates above are given in J2000.0.

The sky on 04 June 2017
Sunrise
05:07
Sunset
20:15
Twilight ends
22:26
Twilight begins
02:57

10-day old moon
Waxing Gibbous

76%

10 days old

Planets
Rise Culm. Set
Mercury 04:16 11:26 18:36
Venus 03:04 09:39 16:14
Moon 15:45 21:28 02:42
Mars 06:08 13:50 21:31
Jupiter 14:50 20:39 02:33
Saturn 20:50 01:31 06:08
All times shown in EDT.

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

03 Jun 2017  –  Venus at greatest elongation west
05 Aug 2017  –  Venus reaches highest point in morning sky
09 Jun 2018  –  Venus reaches highest point in evening sky
17 Aug 2018  –  Venus at greatest elongation east

Image credit

© NASA/Ricardo Nunes

Cambridge

Latitude:
Longitude:
Timezone:

42.38°N
71.11°W
EDT

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