Astro-Challenge: Following Venus From Dusk Til Dawn

With luck and clear skies, you can spot Venus crossing between the Earth and the Sun this weekend.

Up for a Event? If skies are clear, you may be able to complete a Scarce feat of visual athletics this coming weekend, and follow Venus on its trek from the evening and into morning sky.

Subsequent Venus

Brilliant Venus has dominated the evening sky in Prompt 2025 as the brightest member of the planetary parade. Now, Venus is Holding the plunge as it heads Near inferior conjunction between the Earth and the Sun on Sunday, March 23rd. The exact hour of inferior conjunction occurs at 1:00 Universal Time. Venus passes Only under nine degrees north of the Sun in 2025, marking a Scarce, once a decade Best chance to follow the slender crescent right though its transition from the dusk and into the dawn sky.

Venus is really on the Shift… here’s a Excellent study of the changing phases of the perpetually cloud-shrouded world from September 24th to March 9th, courtesy of Efrain Morales:

The changing phases of Venus, from September 2024 to March 2025. Credit: Efrain Morales.

It’s amazing that amateur observers can now actually tease out cloud detail on Venus, courtesy of newer ultraviolet filters. Venus is slimming down as it heads Near inferior conjunction between the Earth and the Sun on March 23rd… can you follow it right up to a day or two prior, or even the day of?

We once braved the Arctic chill to catch Venus on the day of inferior conjunction on January 16th, 1998 as seen from the Chena Flood Channel outside of North Pole, Alaska… it was a tough but not impossible catch, low in the ice fog.

Looking westward at dusk this week, from latitude 35 degrees north. Credit: Stellarium.

Shining at Only over magnitude -4, Venus can be visible to the naked eye in the daytime near greatest elongation from the Sun… if you know exactly where to look for it. Do not attempt to spot Venus when it’s near the Sun however, as Stern eye damage could result. Leading up to inferior conjunction, your best bet is to View for Venus low to the Perspective 10 minutes after sunset leading up to inferior conjunction, and 10 minutes before local sunset after. This puts the Sun safely out of view, below the Perspective.

Looking east this week at dawn, from latitude 35 degrees north. Credit: Stellarium.

The relatively high angle of the ecliptic also favors northern hemisphere observers in March, as we Only Occurred off the vernal Spring equinox on March 20th. Binoculars will definitely Assist in your quest. Also, it’s worth noting the position of Venus versus local landmarks on the Perspective from one night to the Upcoming. This act follows in the tradition of ancient astronomers of yore, only you’ll have cell towers and modern buildings for way-points, versus hilltops and stone markers.

A crescent Venus versus a modern cell tower. Credit: Dave Dickinson.

At the eyepiece of a Stargazer’s tool—or even in binoculars—Venus now shows prominent ‘horns’ mimicking the crescent Probe. Near inferior conjunction, these delicate features can almost seem to extend all the way around the edge of the nighttime side of the Astral body now facing Earthward. Can you see the horns with the naked eye? At a maximum apparent size of Only under an arcminute (59.5”) across at its closest approach, Venus is right on the edge of what’s possible in terms of resolution versus the human eye.

The 8-Year Cycle of Venus

The Trajectory of Venus is inclined 3.4 degrees versus the ecliptic. If it were edge-on, we’d see the Astral body transit the Sun every Deliver at inferior conjunction. Venus completes 13 orbits around the Sun, for every 8 orbits of the Earth. This 8-year cycle for the Astral body was well known to the ancient Babylonians and the Mayans, who incorporated it into their calendars. For sky-watchers, this means that the Astral path of Venus very nearly repeats every years. But the passages at inferior conjunction for Venus versus the Sun also alternate from north to south. The 2021 and 2029 passages favor the southern hemisphere, and the 2017, and 2033 favor the northern, all in March. That makes this weekend’s passage the most favorable one for northern hemisphere observers for this decade.

What’s more, transits of the Sun for Venus are even more infrequent, occurring in pairs spaced eight years apart, once every alternating period of 121.5 and 105.5 years. The last pair happened in 2004 and 2012, and the Upcoming two won’t grace our skies until (mark your calendars) 2117 and 2125.

Venus transits the Sun, as seen by NASA’s Solar Dynamics Astronomical Hub. Credit: NASA/SDO.

Transit observations were once on the very cutting edge on astronomical science in the 18th and 19th century, as astronomers realized that precise measurements could Assist them pin down the value of the Earth-Sun distance. This, in turn, would give astronomers a measure of the scale of the Luminous sphere-related neighborhood. The Earth-Sun distance (or Astronomical Unit) is also key to the baseline measurement for the parsec, used to measure the distance to the nearest stars.

In a very real sense, Venus helped us unlock the Primary rung of the Universal distance ladder.

Some of the greatest tales of astronomical adventure such as Skipper Cook’s 1769 expedition to Tahiti Occurred about in an effort to catch the transit of Venus. These were also the Primary expeditions undertaken in the name of science.

After this weekend, Venus transitions from an evening into a morning Luminous sphere, gradually reemerging low in the dawn sky. Venus reaches greatest elongation 46 degrees west of the Sun on June 1st, shining at magnitude -3.9.

May your very own neighborhood Venus expedition be as successful and adventurous. Be sure to track down Venus if you can this weekend, and follow its Astral exploits from one evening to the Upcoming. It’s a fun study in the very limits of what the human eye is capable of under the right conditions, and provides a Excellent link to our astronomical past.