One great thing about science is how its discoveries continue to confound the experts. Venus has slowed down six minutes and thirty seconds in the past twenty years.
How on earth does that happen? I mean: how in the hell does that happen? The Venus Express probe found that surface features were twelve miles removed from where they should have been, at least according to the findings of the 1990’s Magellan probe.
Planetary scientist Nils Müller did check his numbers:
When the two maps did not align, I first thought there was a mistake in my calculations as Magellan measured the value very accurately, but we have checked every possible error we could think of.
What causes a planet’s rotation to slow down? The big factor might be the thick atmosphere. The Earth’s winds and tides can throw our day off by a millisecond. The actual differences are on the scale of a half-million. Venus’ atmosphere is about a thousand times thicker than Earth’s. That doesn’t seem to add up.
Scientists have been fooled before on planetary days. Saturn’s length of day has been a mystery. It turns out that the Britain-sized moon Enceladus tweaks the magnetic field of the giant planet, throwing off the calculation. Since we’ve yet to detect any solid surface on Saturn, the mistake is understandable. Less so for Venus.
Image above: Venus if stripped of its atmosphere.