Venus at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Venus

Venus will reach half phase in its 1980 morning apparition. It will be shining brightly at mag -4.3.

From Fairfield , this apparition will be well placed and prominent, reaching a peak altitude of 41° above the horizon at sunrise on 9 Sep 1980.

1980 morning apparition of Venus

15 Jun 1980 – Venus at inferior solar conjunction
20 Jul 1980 – Venus at greatest brightness
24 Aug 1980 – Venus at dichotomy
25 Aug 1980 – Venus at greatest elongation west
09 Sep 1980 – Venus at highest altitude in morning sky
07 Apr 1981 – Venus at superior solar conjunction

A graph of the phase of Venus is available here.

Apparitions of Venus

29 Aug 1978 – Evening apparition
18 Jan 1979 – Morning apparition
04 Apr 1980 – Evening apparition
25 Aug 1980 – Morning apparition
10 Nov 1981 – Evening apparition
01 Apr 1982 – Morning apparition
16 Jun 1983 – Evening apparition

Observing Venus

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 days, 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 07h07m10s 19°27'N Gemini 23.7"
Sun 10h14m 10°53'N Leo 31'38"

The coordinates above are given in J2000.0.

The sky on 18 May 2024

The sky on 18 May 2024
Sunrise
05:29
Sunset
20:07
Twilight ends
22:03
Twilight begins
03:33


Waxing Gibbous

85%

10 days old

Planets
Rise Culm. Set
Mercury 04:37 11:15 17:53
Venus 05:21 12:29 19:38
Moon 15:23 21:31 03:28
Mars 03:39 09:57 16:15
Jupiter 05:35 12:49 20:02
Saturn 02:43 08:23 14:03
All times shown in EDT.

Source

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

04 Apr 1980  –  Venus at greatest elongation east
25 Aug 1980  –  Venus at greatest elongation west
09 Sep 1980  –  Venus at highest altitude in morning sky
10 Nov 1981  –  Venus at greatest elongation east

Image credit

© NASA/Ricardo Nunes

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