Astronomisk passage

Et billede af Venus, der passerer Jupiter, som det kunne have set ud d. 3. Januar 1818
Jupiters måne Io passerer Jupiter. Set fra rumsonden Cassini
Saturns måne Dione passerer en anden af Saturns måner Titan. Set fra rumsonden Cassini
Månen passerer Solen. Set fra rumobservatoriet STEREO B. På grund af afstanden synes Månen mindre end set fra Jorden

Den astronomiske begivenhed, hvor to himmellegemer passerer hinanden set fra et bestemt punkt, kaldes en astronomisk passage. Eksempler er Merkurpassage og Venuspassage, hvor planeten passerer foran Solen.

Meget sjældnere end Merkurpassage og Venuspassage er passage af en planet foran en anden planet. Den sidste planetpassage var d. 3. januar 1818, hvor Venus passerede foran Jupiter. Den næste planetpassage vil ske d. 22. november 2065, hvor Venus igen vil passere foran Jupiter. På grund af afstandene vil det være en total formørkelse. Lige før passagen vil Venus yderligere formørke Jupiters måne Ganymedes.

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VtransitsJ.jpg
  • Illustration created using Starry Night Pro software.
  • On 1818-Jan-03, Jupiter was 6.2AU and Venus 1.6AU from the Earth. Both were on the opposite side of the Sun in the constellation Sagittarius and 16 degrees from the Sun in the morning sky.
Moon transit of sun large.ogv
A video of the Moon passing in front of the Sun, as taken by STEREO-B on 25 February 2007 while the spacecraft was about a million miles from Earth. The component photographs were taken in four wavelengths of extreme ultraviolet light. This version of the video is a composite of data from the spacecraft's coronagraph (SECCHI COR1) and extreme ultraviolet imager (SECCHI EUVI).
PIA02879 - A New Year for Jupiter and Io.jpg
Released with Image The Galilean satellite Io floats above the cloudtops of Jupiter in this image captured on the dawn of the new millennium, January 1, 2001 10:00 UTC (spacecraft time), two days after Cassini's closest approach. The image is deceiving: there are 350,000 kilometers -- roughly 2.5 Jupiters -- between Io and Jupiter's clouds. Io is the size of our Moon, and Jupiter is very big.
Saturn system transits.jpg
Four Saturn moons as seen from Cassini. Dione transits Titan by the en:rings of Saturn. Prometheus transits the rings.

In a rare moment, the Cassini spacecraft captured this enduring portrait of a near-alignment of four of Saturn's restless moons. Timing is critical when trying to capture a view of multiple bodies, like this one. All four of the moons seen here were on the far side of the rings from the spacecraft when this image was taken; and about an hour later, all four had disappeared behind Saturn.

Seen here are Titan (5,150 kilometers, or 3,200 miles across) and Dione (1,126 kilometers, or 700 miles across) at bottom; Prometheus (102 kilometers, or 63 miles across) hugs the rings at center; Telesto (24 kilometers, or 15 miles across) is a mere speck in the darkness above center.

The image was taken in visible light with the Cassini narrow-angle camera on Oct. 17, 2005 at a distance of approximately 3.4 million kilometers (2.1 million miles) from Dione and 2.5 million kilometers (1.6 million miles) from Titan. The image scale is 16 kilometers (10 miles) per pixel on Dione and 21 kilometers (13 miles) per pixel on Titan.