© NASA/Ricardo Nunes

Venus at dichotomy

Dominic Ford, Editor
From the Inner Planets feed

Objects: Venus
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Venus will reach half phase in its 1975 evening 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 35° above the horizon at sunset on 13 May 1975.

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1975 evening apparition of Venus

06 Nov 1974 – Venus at superior solar conjunction
13 May 1975 – Venus at highest altitude in evening sky
17 Jun 1975 – Venus at dichotomy
18 Jun 1975 – Venus at greatest elongation east
24 Jul 1975 – Venus at greatest brightness

A graph of the phase of Venus is available here.

Apparitions of Venus

27 Aug 1972 – Morning apparition
13 Nov 1973 – Evening apparition
04 Apr 1974 – Morning apparition
18 Jun 1975 – Evening apparition
06 Nov 1975 – Morning apparition
24 Jan 1977 – Evening apparition
14 Jun 1977 – Morning 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 08h58m30s 19°12'N Cancer 23.4"
Sun 05h43m 23°23'N Taurus 31'29"

The coordinates above are given in J2000.0.

The sky on 28 Sep 2024

The sky on 28 September 2024
Sunrise
06:36
Sunset
18:30
Twilight ends
20:04
Twilight begins
05:01

25-day old moon
Waning Crescent

9%

25 days old

Planets
Rise Culm. Set
Mercury 06:26 12:29 18:31
Venus 09:17 14:28 19:39
Moon 02:14 09:46 17:05
Mars 23:35 07:11 14:47
Jupiter 22:01 05:33 13:05
Saturn 17:43 23:15 04:48
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

13 May 1975  –  Venus at highest altitude in evening sky
18 Jun 1975  –  Venus at greatest elongation east
30 Oct 1975  –  Venus at highest altitude in morning sky
06 Nov 1975  –  Venus at greatest elongation west

Image credit

© NASA/Ricardo Nunes

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Cambridge

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42.38°N
71.11°W
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