Jove comes in

Jupiter on January 20 passes through perihelion, the innermost point of its orbit. Like other heliocentric events, this happens only once in the planet’s orbital period of 12 years (more exactly 11.86).

It doesn’t make much difference, because Jupiter’s orbit is not far from circular: eccentricity 0.049 (where 0 means circular and 1 means a parabola). Jupiter’s mean distance from the Sun is 5.204 AU (astronomical units, Sun-Earth distances), and at perihelion it is 4.951. So at perihelion Jupiter is nearer to the Sun than average by a quarter of an AU, or about 38 million kilometers, which seems a lot but is small in relation to the orbit.

So we don’t expect Jupiter to look noticeably larger at perihelion. Moreover, Earth is at present farther from Jupiter than the Sun is, by 0.35 AU. Last year’s opposition, 2022 Sep. 26, was the nearest to perihelion and therefore the nearest Earth-Jupiter moment in the 12-year cycle.

Here is Jupiter’s orbit as shown on page 117 of Astronomical Calendar 2023

The orange line is from Earth to Jupiter at the opposition, which will come in November.

And here’s the evening scene now.

Jupiter is in Pisces, having recently passed the vernal equinox point (where ecliptic and celestial equator intersect) and moved across the equator into the north celestial hemisphere (on Jan. 13); and, at the time and location of our picture, is 41° above the horizon.

As we hurry on around our smaller orbit, Jupiter will sink lower in the evening sky, and will be behind the Sun on April 11.

Latin Delights Departmemt

Jupiter, as you probably know, is in Latin Juppiter, “Jove-father.” In the other cases the “father” part was dropped – Jovis, “of Jupiter,” etc. – which is why we can also call him Jove,

Spurious is a pejorative word in English – “false, not what it is supposed to be.” Yet in ancient Rome there were respectable men with the name. Most famously, in the tale of “How Horatius Kept the Bridge” against Etruscan besiegers, about 508 BC:

Then up spake Spurius Lartius,
A Ramnian proud was he:
“Lo, I will stand at thy right hand
And keep the bridge with thee.”

How did a proud name become a scornful adjective?

Originally it may have been an Etruscan word spurie, meaning “city-dweller,” though this is only a guess by scholars; no one knows. There were Romans of Etruscan descent. The Romans themselves didn’t know what the word meant, and someone made a jokey suggestion, as ridiculous as folk-etymologies usually are: it stood for sine patre filius, “son without a father,” born out of wedlock. So the use of the name died out in later centuries; it was suspected of being just a word for “bastard,” and no one wanted to give that name to his son. Borrowed into English, spurious came to mean “illegitimate” in various senses.

There was in early Islamic history (in the 600s AD) an important politician called Ziyâd ibn Abîhi: “Ziyâd son of his father – son of whoever his father was.”

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