Archive
09/24/2021 – Ephemeris – Capricornus, home this season to Jupiter and Saturn
This is Bob Moler with Ephemeris for Friday, September 24th. Today the Sun will be up for 12 hours and 3 minutes, setting at 7:35, and it will rise tomorrow at 7:33. The Moon, halfway from full to last quarter, will rise at 9:26 this evening.
Nearly 2000 years ago the southernmost of the constellations of the zodiac was Capricornus the water goat. That’s why the latitude on the Earth where the Sun is overhead on the winter solstice is called the Tropic of Capricorn. Not anymore, Sagittarius, one constellation west, has that honor today*. Capricornus is large, but made up of dim stars. To me, it looks like a 45 degree isosceles triangle, long side up, but which all the sides are sagging. The constellation is found low in the south at 10 to 11 p.m. The image that is supposed to be represented by the stars is that of a goat whose hind quarters are replaced by a fish’s tail, not a mermaid but a mer-goat. This autumn, Jupiter is at the left end of Capricornus, with Saturn on the right.
The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT-4 hours). They may be different for your location.
The reason for the shift is lunisolar precession, which I talked about yesterday.
Addendum
Capricornus w/Jupiter & Saturn finder animation for 10 pm, September 24, 2021. Created using Stellarium and GIMP.
09/14/2020 – Ephemeris – Not exactly a mermaid
This is Bob Moler with Ephemeris for Monday, September 14th. Today the Sun will be up for 12 hours and 33 minutes, setting at 7:54, and it will rise tomorrow at 7:22. The Moon, 3 days before new, will rise at 4:42 tomorrow morning.
Nearly 2000 years ago the southernmost of the constellations of the zodiac was Capricornus which is a water goat. That’s why the latitude on the Earth where the Sun is overhead on the winter solstice is called the Tropic of Capricorn. Not any more, Sagittarius, one constellation west past Jupiter and Saturn this year, has that honor today. Actually Capricornus does need the press. It’s large, but made up of dim stars. To me it looks like a 45 degree isosceles triangle, long side up, but which all the sides are sagging. The constellation is found low in the south-southeast at 10 p.m. The image that is supposed to be represented by the stars is that of a goat whose hind quarters are replaced by a fish’s tail, not a mermaid but a mergoat.
The event times given are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Capricornus finder animation for September 14, 2020 at 10 pm for western Michigan. Note that the Teapot of Sagittarius is pouring its contents on the southwestern horizon is to the right. Created using Stellarium and GIMP.
Important seasonal latitudes on the Earth. Source: worldatlas.com
09/14/2015 – Ephemeris – Another odd creature of the Zodiac, a sea-goat
Ephemeris for Monday, September 14th. The Sun will rise at 7:20. It’ll be up for 12 hours and 35 minutes, setting at 7:55. The Moon, 1 day past new, will set at 8:35 this evening.
As the Teapot of the constellation Sagittarius tilts and pours celestial tea on the southwestern horizon, it is followed in the south-southeast by the faint constellation of Capricornus the sea-goat. I’m not sure you’ll see a half goat with a fish’s tail here unless you’ve started Oktoberfest a bit early. To me, it looks like a big sagging triangle with the point down. Capricornus is a constellation of the zodiac, and its claim to fame is a latitude line on the globe at 23 and a half degrees south, called the Tropic of Capricorn. Back a couple of thousand years ago the sun entered Capricornus on the first day of winter, the winter solstice. Thus the latitude where the sun was overhead at that instant was called the Tropic of Capricorn. Due to the wobble of the earth’s axis, the line should now be called the Tropic of Sagittarius.
Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Capricornus represented in Cartes du Ciel
An artist’s rendering of Capricornus. A part of Stellarium’s functionality. The constellation lines are drawn differently than Cartes du Ciel
09/27/11 – Ephemeris – The constellation of Capricornus
Tuesday, September 27th. The sun will rise at 7:35. It’ll be up for 11 hours and 55 minutes, setting at 7:30. The moon is new today, and won’t be visible.
As the Teapot of the constellation Sagittarius tilts and pours celestial tea on the southwestern horizon, it is followed in the south by the faint constellation of Capricornus the sea goat. I’m not sure you’ll see a half goat with a fish’s tail here unless you’ve started Oktoberfest a bit early. To me, it looks like a big sagging triangle with the point down. Capricornus is a constellation of the zodiac, and its claim to fame is a latitude line on the globe at 23 and a half degrees south, called the Tropic of Capricorn. Back a couple of thousand years ago the sun entered Capricornus on the first day of winter, the winter solstice. Thus the latitude where the sun is overhead at that instant was called the Tropic of Capricorn. Due to the wobble of the earth’s axis, the line should be called the Tropic of Sagittarius.
* Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.
Addendum
Capricornus as represented in Cartes du Ciel
Capricornus as represented in Stellarium
Bob Moler's Ephemeris Blog 