Venus at dichotomy

Dominic Ford, Editor
From the Inner Planets feed


Objects: Venus

Venus will reach half phase in its 1978–1979 morning apparition. It will be shining brightly at mag -4.4.

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 23 Dec 1978.

1978–1979 morning apparition of Venus

07 Nov 1978 – Venus at inferior solar conjunction
11 Dec 1978 – Venus at greatest brightness
23 Dec 1978 – Venus at highest altitude in morning sky
17 Jan 1979 – Venus at dichotomy
18 Jan 1979 – Venus at greatest elongation west
25 Aug 1979 – Venus at superior solar conjunction

A graph of the phase of Venus is available here.

Apparitions of Venus

24 Jan 1977 – Evening apparition
14 Jun 1977 – Morning apparition
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

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 16h39m10s 18°29'S Ophiuchus 24.9"
Sun 19h59m 20°37'S Sagittarius 32'30"

The coordinates above are given in J2000.0.

The sky on 23 Nov 2024

The sky on 23 November 2024
Sunrise
06:43
Sunset
16:15
Twilight ends
17:54
Twilight begins
05:03


Waning Crescent

43%

22 days old

Planets
Rise Culm. Set
Mercury 08:33 12:55 17:17
Venus 10:09 14:32 18:54
Moon 23:09 06:06 12:50
Mars 20:36 04:03 11:30
Jupiter 17:09 00:40 08:11
Saturn 12:58 18:29 23:59
All times shown in EST.

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

23 Dec 1978  –  Venus at highest altitude in morning sky
18 Jan 1979  –  Venus at greatest elongation west
03 Apr 1980  –  Venus at highest altitude in evening sky
04 Apr 1980  –  Venus at greatest elongation east

Image credit

© NASA/Ricardo Nunes

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