Archive | January, 2016

Solstices and equinoxes D.1.25

24 Jan

The constellations are associated with solstices and equinoxes.

About 3,000 years ago, or around when the Babylonians were active, the Sun appeared in the constellation of Cancer at the summer solstice, but it now appears in Gemini.

And you can see the impact of precession on any world map because it’s marked as the latitude at which the sun was directly overhead, 3,000 years ago, at 23 degrees north, that’s why it’s called the Tropic of Cancer.

Similarly, the southern one is the Tropic of Capricorn, because on the solstices on those days, the sun would be directly overhead. But the Sun is no longer directly overhead in Cancer because of precession, it’s now in Gemini.

When astrology began about 3,000 or so years ago, your sign was the constellation in which the sun appeared on your date.

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Polaris and Vega Stars D.1.24

23 Jan

The earth’s rotation wobbles just like a top does. This happens on a very long time scale. This is not a yearly occurrence but instead this cycle takes about 26,000 years to complete a full cycle.

Currently, the earth’s rotation access points toward the star Polaris. The star Polaris is the marker for going north at night.

In 13,000 years when it’s halfway through its precession cycle, the Earth’s rotation pull is going to be pointed more in the direction of the star of Vega.

So Polaris will no longer be the north beacon that it is now. And then in another 13,000 years later this earth’s top will wobble around and we will be back to Polaris on 26,000 year time scales.

So the precession as it wobbles around does not change the axis tilt, it’s always 23.5 degrees.

The Seasons D.1.23

22 Jan

The seasons are caused by the 23.5 degree tilt of Earth’s rotation axis. The celestial sphere is tilted by 23.5 degrees.

The rotation pole which is tilted 23 degrees relative to the north ecliptic pole, which would then be perpendicular to the ecliptic pole.

There is this 23.5 degree angle between the orbital plane and the Celestial Equator.

And as Earth rotates, or orbits, the Sun, that 23.5 degree angle always remains constant.

Days and Months of the Year D.1.22

21 Jan

There are 360 degrees in a circle.

There are 365 days in a year. The orbital period of the Earth go back to the Babylonians, 360 is close to 365. And most importantly, 360 is evenly divisible by 12.

So it comes out to be 30, which is the number of days in the 12 months. And so we have 12 hours in the day, 12 hours at night, 12 months of the year, and 360 degrees in a circle.

All of this astronomy, this planetary astronomy is from the ancients – the Babylonians.

The Sun moves about a degree a day.

The Earth is inclined D.1.21

20 Jan

The Milky Way is our galaxy and it’s shaped rather like a flat disk and bulges in the center, with many more stars in the center of the galaxy.

Where I stand the stars basically move east to west on a night sky and they rotate basically in a straight line on a celestial sphere.

The Earth is inclined on an axis, relative to the celestial sphere. And so at my altitude, my zenith, that 90 degree angle above my head, is not always lined up with the celestial North Pole from where I’m observing. So if I’m standing at 40 degrees latitude, I’ll be able to have that exactly above my head.

If I was at the North Pole, I will always see the same stars, no matter what time of the year it is.

But if I was located at the equator, I will see different stars depending on the time of year, because my inclination relative to the celestial North Pole is changing.

North, there’ll be some stars that apparently never rise or set. Those are the ones that are circumpolar stars. And they always stay in the night sky because they’re very close to the celestial North Pole. And you will always see them because they never actually dip below the horizon. There are circumpolar stars, and then there are stars that rise and set.

From different locations on the globe you can see different stars.

Zodiac Signs in the Sky D.1.20

19 Jan

All the planets and the Sun pass through a small number of constellations in our night sky. These constellations are actually the zodiac signs.

We associate with 12 zodiac signs with each month of the year.

As it is there are 13 constellations, the additional one is Ophiuchus.

12 is a curious number. We have 12 hours a day, 12 hours at night. We have 12 months, 12 signs of the zodiac.

It is from the Babylonians we get this base 12 counting system.

At the moment there are 86 constellations, and they’re not actually associated with patterns in the night sky. They’re actually associated with the regions in the night sky where particular patterns that the ancients might have recognized as being a mythical creature or something from the night sky.

Days of the Week by the Planets D.1.19

18 Jan

In a really dark area you can see about 6,000 stars on a given night – But with a modern telescope there are many more to be seen.

The seven days of the week are denoted to a planet and are the seven wanderers.

Sunday – Sun’s Day

Monday – Moon’s Day

Tuesday – Tiu’s Day

Wednesday – Woden’s Day

Thursday – Thor’s Day

Friday – Freya’s Day

Saturday – Saturn’s Day

Each day is denoted to a planet. Our names come from the North Celtic, barbarians, from invading Rome.

So as these planets orbit the Sun, these seven wanderers, pass through constellations in the celestial sphere.