Wednesday, March 14, 2012

3-D

So, we watched for the last few weeks as Venus and Jupiter drew closer together in the evening sky. Who needs television when such beauty is there for the taking? Last night they made their closest approach.

But, of course, their conjunction was only apparent, along the same line of sight. In real space they were actually moving farther apart as Venus, swinging around the Sun, ran away from Jupiter and toward the Earth.

Who first conceived the third dimension of the night sky? Who first punctured the celestial sphere, blasted open the dome of night, sent the planets racing on their own orbits? By the 3rd century B.C.E. the Alexandrians had inflated the cosmos sufficiently to give the Sun, Moon and planets space to perform their respective dances.

And now Venus races towards Earth (it will overtake us in May). Jupiter plods way out there (as seen from Earth, it will dawdle in Taurus for most of the year).

And the show goes on. On March 25 a thin crescent Moon will join Jupiter. The next night it will pass Venus, with the Pleiades not far away. Alas, I will be back in New England by then, without my glorious, unimpeded tropical horizon.

Here is yesterday's APOD (Astronomy Picture of the Day), a glimpse into the third dimension that the Alexandrian astronomers could never have imagined. The streak of an artificial satellite in Earth's atmosphere. Myriad stars of the Milky Way. And winking beyond, millions of light-years away, a cluster of galaxies.