© NASA/Ricardo Nunes

Venus at greatest elongation east

Dominic Ford, Editor
From the Inner Planets feed

Please wait
Loading 0/4
Click and drag to rotate
Mouse wheel to zoom in/out
Touch with mouse to dismiss
The sky at

Venus will be well placed for observation in the evening sky, shining brightly at mag -4.4.

From Ashburn, it will be difficult to observe as it will appear no higher than 16° above the horizon. It will become visible at around 18:28 (EST) as the dusk sky fades, 16° above your south-western horizon. It will then sink towards the horizon, setting 2 hours and 21 minutes after the Sun at 20:31.

Begin typing the name of a town near to you, and then select the town from the list of options which appear below.

Venus's orbit lies closer to the Sun than the Earth's, meaning that it always appears close to the Sun and is very difficult to observe most of the time.

It is observable only for a few weeks each time it reaches greatest separation from the Sun – moments referred to as greatest elongation.

On these occasions, however, 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 or evening star.

These apparitions take place alternately in the morning and evening skies, depending whether Venus lies to the east of the Sun or to the west.

When it lies to the east, it rises and sets a short time after the Sun and is visible in early evening twilight. When it lies to the west of the Sun, it rises and sets a short time before the Sun and is visible shortly before sunrise.

On this occasion, it lies 47° to the Sun's east.

Venus in coming weeks

The key moments in this apparition of Venus are as follows:

28 Oct 2021 10:24 EDT – Venus at dichotomy
29 Oct 2021 10:44 EDT – Venus at greatest elongation east
07 Dec 2021 11:08 EST – Venus at greatest brightness
08 Jan 2022 19:42 EST – Venus at inferior solar conjunction

After greatest elongation, the distance between Venus and the Sun will decrease each night as it sinks back into the Sun's glare. The table below lists how long Venus will remain up after sunset each night; all times are given in Ashburn local time.

Date Sun
sets at
Venus
sets at
Altitude of Venus
at sunset
Direction of Venus
at sunset
22 Oct 202118:1820:3217°south-west
29 Oct 202118:0920:3218°south-west
05 Nov 202118:0120:3418°south-west
12 Nov 202116:5419:3519°south-west
19 Nov 202116:4819:3720°south-west
26 Nov 202116:4519:3621°south-west
03 Dec 202116:4319:3121°south-west
10 Dec 202116:4219:2221°south-west
17 Dec 202116:4419:0520°south-west
24 Dec 202116:4718:3917°south-west
31 Dec 202116:5218:0512°south-west

A graph of the angular separation of Venus from the Sun around the time of greatest elongation is available here.

Venus's position

The position of Venus when it reaches greatest elongation will be:

Object Right Ascension Declination Constellation Magnitude Angular Size
Venus 17h28m40s -26°54' Ophiuchus -4.4 24.9"
Sun 14h15m -13°33' Virgo -26.7 32'12"

The coordinates above are given in J2000.0.

Seasonal effects

At each apparition, Venus reaches a similar separation from the Sun – around 48°. This distance is set by the geometry of how big Venus's orbit is, and how far away it is from the Earth.

Nonetheless, some times of the year are more favourable for viewing Venus than others.

It appears most favourably in the evening sky around the time of the local spring equinox, and most favourably in the morning sky around the local autumn equinox.

These dates are reversed in the northern and southern hemispheres, such that a good apparition in one hemisphere will not be easily observable from the other.

This is comes about because Venus always lies close to the line of the ecliptic, shown in yellow in the planetarium above. This is the line through the zodiacal constellations that the Sun follows through the year, and marks the flat plane in space in which all of the planets circle the Sun.

When Venus remains in the sky for a few hours after the Sun has set, its altitude above the horizon depends on two factors.

One is its angular separation from the Sun. But equally important is how steeply the line of the ecliptic is inclined to the horizon.

If Venus is widely separated from the Sun along the ecliptic, this may not translate into a high altitude if the ecliptic meets the horizon at a very shallow angle, running almost parallel to it.

Conversely, if the ecliptic is almost perpendicular to the horizon, a much smaller separation from the Sun may place Venus higher in the sky.

The inclination of the ecliptic plane to the horizon at Ashburn varies between 74° (sunset at the spring equinox) and 27° (sunset at the autumn equinox). On October 29, the ecliptic is inclined at 30° to the western sunset horizon, as shown by the yellow line in the planetarium view above, meaning that on this occasion Venus is poorly placed for viewing from Ashburn.

The sky on 29 October 2021
Sunrise
07:33
Sunset
18:11
Twilight ends
19:41
Twilight begins
06:03

23-day old moon
Waning Crescent

42%

23 days old

Planets
Rise Culm. Set
Mercury 06:04 11:49 17:35
Venus 11:39 16:06 20:32
Moon 00:27 07:47 15:07
Mars 06:58 12:25 17:53
Jupiter 15:03 20:15 01:31
Saturn 14:16 19:13 00:14
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

29 Oct 2021, 10:44 EDT  –  Venus at greatest elongation east
20 Mar 2022, 17:22 EDT  –  Venus at greatest elongation west
04 Jun 2023, 11:58 EDT  –  Venus at greatest elongation east
23 Oct 2023, 19:51 EDT  –  Venus at greatest elongation west

Image credit

© NASA/Ricardo Nunes

Ashburn

Latitude:
Longitude:
Timezone:

39.04°N
77.49°W
EST

Color scheme