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Venus at greatest brightness

Dominic Ford, Editor
From the Inner Planets feed

Objects: Venus
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The sky at

Venus will reach its greatest brightness in its 2015–2016 morning apparition. It will be shining brightly at mag -4.5.

From Fairfield , this apparition will be well placed and prominent, reaching a peak altitude of 41° above the horizon at sunrise on 14 Oct 2015.

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
sets at
rises at
at sunrise
at sunrise
25 Aug 201506:1505:1511°north-west
04 Sep 201506:2504:2122°north-west
14 Sep 201506:3503:4431°north-west
24 Sep 201506:4503:2337°north-west
04 Oct 201506:5503:1440°north-west
14 Oct 201507:0603:1441°north-west
24 Oct 201507:1703:2041°north-west
03 Nov 201506:2902:3140°north-west
13 Nov 201506:4102:4539°west
23 Nov 201506:5303:0137°west
03 Dec 201507:0403:2034°west
13 Dec 201507:1203:4031°west
23 Dec 201507:1904:0127°west
02 Jan 201607:2104:2224°west
12 Jan 201607:2004:4321°west

A graph of the brightness of Venus is available here.

Observing Venus

The 2015–2016 morning apparition of Venus
15 Aug 2015 – Venus at inferior solar conjunction
20 Sep 2015 – Venus at greatest brightness
24 Oct 2015 – Venus reaches highest point in morning sky
25 Oct 2015 – Venus at dichotomy
26 Oct 2015 – 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 brightness

Venus's brightness depends on two factors: its closeness to the Earth, and its phase. Its 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 reaches its brightest when it is still a crescent – with less than half of its disk illuminated. This is because it is much closer to the Earth during its crescent phases than at other times.

As a result, during evening apparitions, Venus reaches maximum brightness a few days after it is at greatest separation from the Sun, which always coincides with it showing half-phase (dichotomy).

Conversely, during morning apparitions, Venus reaches maximum brightness a few days before it is at greatest separation from the Sun.

Venus's position

The coordinates of Venus when it reaches its greatest brightness will be:

Object Right Ascension Declination Constellation Angular Size
Venus 09h15m20s +10°57' Cancer 38.4"
Sun 11h50m +01°02' Virgo 31'51"

The coordinates above are given in J2000.0.

The sky on 20 September 2015
Twilight ends
Twilight begins

7-day old moon
Waxing Crescent


7 days old

Rise Culm. Set
Mercury 08:17 13:46 19:15
Venus 03:30 10:12 16:54
Moon 13:25 18:23 23:20
Mars 04:03 10:55 17:48
Jupiter 05:03 11:39 18:14
Saturn 11:53 16:49 21:45
All times shown in EDT.


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

20 Sep 2015  –  Venus at greatest brightness
24 Oct 2015  –  Venus reaches highest point in morning sky
25 Oct 2015  –  Venus at dichotomy
26 Oct 2015  –  Venus at greatest elongation west

Image credit

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