Thanks to Jon Moss, I witnessed the conjunction of Venus, Mars and the Moon last night (February 20, 2015) before they set. The clear, dry air here made them vivid. Mars was dim, maybe on the far side of its orbit. Of course, compared to Venus and the Moon, everything in the night sky is dim.
If I’d looked close (as in, binocular close), I might have detected the phase of Venus. (My cataracts impede clarity.)
I was just reading about Venus: I didn’t realize—or had forgotten—that Venus has no magnetic field, and that may be why it’s so different from Earth, which it otherwise approximates in size, mass and composition. It doesn’t have a strong magnetic field because it’s internal structure doesn’t work like an electric dynamo, as Earth’s does, to create the field.
Which raises the question: how rare is that dynamo effect? Do most Earth-like planets have a strong magnetic field? If not, they’re likely to more resemble Venus than Earth so far as in-habitability–not to mention any life–is concerned. Venus has no life. In fact, it has not water. The water it may have once had has “disassociated” due to its lack of a magnetic field, and the heat and pressure. It’s the hottest planet; hotter than Mercury.
Not only that, but Venus is the only planet that rotates retrograde. And it’s “day” is longer than its “year.” That all suggests something very strange happened to Venus four or five billion years ago. Or not.
To borrow the wording of J. B. S. Haldane, “reality is not only weirder than you imagine; it’s weirder than you can imagine.”