These three photos were taken over six minutes, and show how our planet’s spin gives us our day: of light and dark. While it looks as if the tower has laid an egg, and left it behind; or sent it rolling up the hill, in fact it is our planet spinning around, with this location now facing the sun giving it ‘morning’.
Last month, I saw Jupiter and Saturn ‘drop into the horizon’ after their conjunction; which was again because of our planet spinning. They were both only visible for a short time then, just above the horizon; and didn’t take long at all to ‘drop out of the sky’ behind some trees.
After Saturn (looking fainter as smaller and farther away) had been at 10 o’ clock to Jupiter all year; if Jupiter was the middle of the ‘clock face’; in December Jupiter overtook Saturn as it is on the inside in the solar system, and so Saturn then looked at 4 o’ clock.
Jupiter’s orbit is 11.86 years and Saturn’s is 29.46 years.
Turned out to be a nice sunny afternoon and quite spectacular POP (PinkyOrangePurple) sunset, inspiring this poem:
Hori-sun Set-flocks Free-Jupiter
December sun skirts horizon. Are bird flocks weighing it down? Those that fly its sunset sky. From its landing dipping direction. V-shape swirls slowly enlarging. Coasting home after day’s work? Flying over before twilight colours. Prelude to night Jupiter first light.
Jupiter and Saturn visibility has travelled across the southern sky over the year, westward from south-east to middle now: that’s because they’re on the ‘outside lane’ and we’re overtaking on the inside. In contrast to our year (365 days; time measurement created by humanity of course) orbit it takes Jupiter 11.86 years to orbit the sun, and Saturn 29.50, so they are not always seen close together like that; Jupiter will ‘race’ ahead of Saturn.
They also look like they’re travelling westwards each night, but that’s because of our planetary spin. In contrast, Venus is on our inside, taking only 224 ‘days’ to orbit the sun, so is racing ahead, looking as if it’s travelling eastward on our horizon over the year.
It was Galileo’s observationsof the full planetary phases of Venus in 1610 that determined planets orbit the sun, rather than Earth.
Venus still looks as if it’s travelling west through the night though, because that’s defined by our planetary spin. As Jupiter lags behind us we see it earlier as our planet twists around anti-clockwise:
Jupiter 12.49 (November 5th) to 11.07 (December 5th) As Venus races ahead, we see it later: Venus 3.54 (November 5th) to 5.32 (December 5th)
Eventually, Venus will go out of sight behind the sun, reappearing in our evening as it catches up with us again. This year (2020), space.comwrites Venus was in our: Evenings in the western sky at dusk from January 1st to May 24th; mornings in the eastern sky at dawn from June 13 to Dec. 31.
DAILY SPIN: THE SUN REMAINS THE SAME [double play of words: the first affectionately parodying a newspaper, while the second paraphrases Led Zeppelin’s album, The Song Remains the Same]
If you watch another planet or two (good sight of Jupiter and Saturn in the southern sky with the moon again last night) through a window you can see our movement: as the planets seem to slowly travel across the window before leaving sight.
Earth’s spin is the same reason for our daily view of the sun. The sun remains the same through time though, as we orbit it,
The other planets are also orbiting it, so their positions in ‘our night sky’ change. We are on the ‘inside lane’ of Jupiter and Saturn, so will race ahead soon, and they won’t be in our ‘outside lane’ vison.
Our daily/nightly sight of the moon is different, because it orbits us.
End of Days
Leaving days, we leave our planet’s spin influence.
The seasons are not because of our planet’s spin. They are because of our Earth’s rigid 23.4 axis tilt, which means that as we orbit the sun over the course of our year, each north-south hemisphere has half a year pointing towards the sun and then space, or just out to space.
Our planet’s spin still gives both hemispheres day and night, although there is more/less depending on where we are in the orbit (year). Now, the northern hemisphere is pointing more and more to space, so we will have more and more darkness; the southern is pointing more and more towards the sun, so it will have more light.
I hope the above combination of artistic imagination and writing explanation can be useful to your enjoyment of the night sky. I’ve been passively learning about it all my life, but my writing and researching over the last fifteen years made me more active. Theplanetstodayand timeanddatewebsites have recently been very useful in giving me a clear image of our solar system and its timings.
The above is the kind of knowledge I wanted 11 years ago when I started this website. That it has taken this long shows that you can’t rush these kinds of things, and knowledge is not always available; or not available in the style you need. In another 11 years we will know much more, and one day we may know how our universe works the way we today know how our solar system does.
Hi, it’s Stephen Wolfing, cosmology expert at the Greenygrey.
One big space story today. A month after Marc Latham’s Night Sky poem, a Yahoo article reports that Venus and Jupiter are set to closely meet again over the moon in the next couple of northern hemisphere night skies.
A month after the Valentine Night Sky poem, Venus and Jupiter are set to closely meet again over the moon in the next couple of northern hemisphere night skies.
Marc Latham’s latest Folding Mirror poem mixes up Valentine week with news from the One Minute Astronomer newsletter that Venus and Jupiter are getting very close this month, and will also have the moon near them at certain times. The photo above, copied from the One Minute Astronomer site, shows what it should look like. Here’s the poem:
Valentine Night Sky
Venus sings love songs
on a winter residency
starting after sundown
dazzling through the night
visage allure attracts valentine
planet travelling across sky
toward the enchantress
over a horizon moon
Jupiter serenades my star
mistYmuse 