Glossary term: Conjunction

Description: From the perspective of an observer on Earth, when two astronomical objects appear to be in close proximity in the sky they are said to be in conjunction. The conjunction does not need to be actually visible – for instance, the Moon and the Sun are approximately lined up whenever there is a new Moon, but we cannot see the Moon under those conditions, unless there is a solar eclipse. In that case, and whenever a conjunction is so close that one object appears to cover the other, astronomers would describe it as a transit or eclipse.

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Term and definition status: This term and its definition have been approved by a research astronomer and a teacher

The OAE Multilingual Glossary is a project of the IAU Office of Astronomy for Education (OAE) in collaboration with the IAU Office of Astronomy Outreach (OAO). The terms and definitions were chosen, written and reviewed by a collective effort from the OAE, the OAE Centers and Nodes, the OAE National Astronomy Education Coordinators (NAECs) and other volunteers. You can find a full list of credits here. All glossary terms and their definitions are released under a Creative Commons CC BY-4.0 license and should be credited to "IAU OAE".

Related Media

Three bright objects in the sky with one top left, one in the middle and one lower centre.

Jupiter, Venus, Moon Conjunction

Caption: Captured with a smartphone in February 2023, over the skies of Luzerne County, Pennsylvania, USA, this photograph offers a glimpse into a conjunction, an enthralling astronomical phenomenon that occurs when two or more celestial objects are seen in close proximity in the sky from our perspective, despite the objects not being physically near to each other. In this image, the brilliance of Jupiter (top), the allure of Venus (middle), and the familiar glow of our Moon (bottom) dance together against a backdrop of delicate clouds and a treeline silhouette, making it a moment worth treasuring.
Credit: Joslynn Appel/IAU OAE (CC BY 4.0)

License: CC-BY-4.0 Creative Commons Attribution 4.0 International (CC BY 4.0) icons