Astronomy Essentials

Venus before sunrise: Greatest elongation October 23, 2023

Venus at greatest elongation: Sky chart of bright Venus and many labeled constellations and stars.
Venus before sunrise. Venus will be at greatest elongation – farthest from the sunrise – on October 23, 2023. Look for Venus in the sunrise direction before dawn breaks, and as the sky is lightening. If you have a dark sky look for the constellation Leo the Lion in the direction of Venus. Image via Stellarium.

Venus will be farthest from the sunrise in October, 2023. For the Northern Hemisphere, it’ll be the 2nd planet’s best morning apparition for the year.

When to watch: Venus races between the Earth and sun in August 2023, then emerges quickly into the eats before sunrise, to remain visible there until around May 2024. Greatest elongation – when Venus will be farthest from the sunrise – is mid- to late October 2023.
Where to look: Look in the sunrise direction, while the sky is still dark or just getting light. You can’t miss Venus as the very bright morning “star.”
Greatest elongation is 16 UTC on October 23, 2023 (source: AstroPixels).
Note: As the sun’s 2nd planet, Venus is bound by an invisible tether to the sun in our sky. It’s always east before sunrise, or west after sunset (never overhead at midnight). Venus is the brightest planet visible from Earth and shines brilliantly throughout every morning or evening apparition. Greatest elongation happens when Venus is farthest from the sun on the sky’s dome. At the October 2023 greatest elongation, Venus will appear higher in the sky from the Northern Hemisphere than from the Southern Hemisphere due to the steep angle of the ecliptic (path of the sun, moon and planets) on autumn mornings.

At greatest elongation in October 2023:

– Venus’s distance from sun on the sky’s dome is 46 degrees.
– Venus shines with dazzling brightness at magnitude -4.4
– Through a telescope, Venus appears 50% illuminated, in a 3rd quarter phase, 24 arcseconds across.

For precise sun and Venus rising times at your location:

Old Farmer’s Almanac (U.S. and Canada)

Timeanddate.com (worldwide).

Stellarium (online planetarium program)

Venus events, 2023 – 2024

Aug 13, 2023: Inferior conjunction (races between Earth and sun)
Oct 23, 2023: Greatest elongation (morning)
Jun 4, 2024: Superior conjunction (passes behind sun from Earth)

A comparison of elongations

Morning elongations of Venus (or Mercury) are best around the autumn equinox (around September for the Northern Hemisphere, around March for the Southern Hemisphere). These elongations, called western elongations because Venus is west of the sun, happen when the ecliptic – path of the sun, moon and planets – makes a steep angle to the morning horizon. A steep ecliptic angle keeps the planets more directly above the sunrise or sunset.

Springtime elongations that occur in the morning (around March for the Northern Hemisphere, around September for the Southern Hemisphere) are less glorious because of the shallow angle of the ecliptic. When the ecliptic makes a shallow angle with respect to the horizon, that angle keeps the planets closer to the bright sun’s rays.

Chart showing the ecliptic slanting up and to the right in the morning near the equinoxes.
This image shows the path of the ecliptic in the morning sky around the fall and spring equinoxes.

Bottom line: At greatest elongation on October 23, 2023, Venus is as far from the sunrise as it will be for this morning apparition.

Posted 
January 1, 2023
 in 
Astronomy Essentials

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