La danse de Venus et la Terre
Every time Venus passes the Earth, it shows the same face.
This
remarkable fact has been known for only
about 50 years, ever since
radio telescopes
have been able to peer beneath
Venus' thick clouds and track its slowly rotating surface.
This
inferior conjunction -- when Venus and Earth are the closest --
occurs today.
The featured animation
shows the positions of the Sun, Venus and Earth between 2010-2023 based on
NASA-downloaded data,
while a mock yellow 'arm' has been fixed to the ground on Venus to indicate rotation.
The reason for this unusual 1.6-year resonance
is the
gravitational influence that Earth has on Venus, which
surprisingly dominates the Sun's tidal effect.
If Venus could be seen through the
Sun's glare today,
it would show just a
very slight sliver of a
crescent.
Although previously
visible in the evening sky, starting tomorrow,
Venus
will appear in the morning sky --
on the other side of the Sun as viewed from Earth.