Reality and simulation in the 2012 transit of Venus

The first part of this video shows the transit of Venus on 5-6 June 2012 as seen from SWAP, a solar imager onboard ESA's PROBA-2 microsatellite. SWAP, watching the Sun in EUV light, observes Venus as a small, black circle, obscuring the EUV light emitted from the solar outer atmosphere - the corona - from 19:45 UT onwards. At 22:16 UT - Venus started its transit of the solar disk.

 

Credit: NASA/Goddard Space Flight Center/SDO

The bright dots all over the image ('snow storm') are energetic particles hitting the SWAP detector when PROBA-2 crosses the South Atlantic Anomaly, a region where the protection of the Earth magnetic field against space radiation is known to be weaker. Note also the small flaring activity in the bright active region in the northern solar hemisphere as Venus passes over. Towards the end, you can see a big dim inverted-U-shape moving away from the Sun towards the bottom-right corner. This is a coronal mass ejection taking off.

The second part of the video is constructed combining high-definition images of the transit of Venus captured by NASA's Solar Dynamics Observatory (SDO) across different wavelengths. The red colored sun is the 304 angstrom ultraviolet, the golden colored sun is 171 angstrom, the magenta sun is 1700 angstrom, and the orange sun is filtered visible light. 304 and 171 show the atmosphere of the sun, which does not appear in the visible part of the spectrum. 

Movie showing an artist's conception of the 2012 Venus transit. Starting on the surface of Venus, the camera pulls up through the planets clouds and flies back towards Earth to watch Venus's transit accross the Sun. Credit: NASA/Goddard Space Flight Center Conceptual Image Lab

Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio

In the above visualization, there are a few things which should be noted.

1. A transit is when a planet passes directly between the Sun and the Earth and we see the planet as a small dot moving slowly across the face of the Sun.
2. The camera view is NOT from anywhere on the surface of the Earth, but corresponds to an observer positioned along the Earth-Sun line, but over the north pole of the Earth. This causes the path of Venus to cross the solar disk lower (closer to the solar equator) than it would appear to an observer on the surface of the Earth.

This visualization was developed for conceptual illustration and not meant for precision scientific use.

Sources:

• SDO's Ultra-high Definition View of 2012 Venus Transit, Goddard Multimedia, June 6, 2012
• 2012 Venus Transit, Conceptual Image Lab at GFSC, March 29, 2012
• Venus Transit - 2012, Scientific Visualization Studio at GFSC, April 12, 2012