Transcript for Jan 5 - 11

RACHEL
Welcome to Idaho Skies for the second week of January. We’re your hosts, Rachel…

PAUL
…and Paul.

RACHEL
Earth reaches perihelion on January 4th.

PAUL
As many people know, Earth’s orbit around the sun is not perfectly circular.

RACHEL
It follows a mathematically-precise oval shape called an ellipse.

PAUL
Because of Earth’s elliptical orbit, we’re 3 million miles closer to the sun on January 4th than in July.

RACHEL
The laws of gravity dictate that Earth’s orbital speed around the sun will also be at its greatest today.

PAUL
This means winter in the northern hemisphere is several days shorter than its summer.

RACHEL
Mighty Jupiter reaches opposition on the 5th.

PAUL
Opposition is a point in space opposite the sun, that is, relative from our perspective.

RACHEL
At opposition, a planet beyond Earth is its closest to us.

PAUL
This makes the planet its largest and brightest in our sky.

RACHEL
Speaking of Jupiter, one of astronomy’s most momentous events occurred 404 years ago starting on the 7th.

PAUL
In 1610, Galileo Galilei turned his new telescope towards Jupiter and discovered that four large moons circled the planet.

RACHEL
Up until this time, most learned people believed that all heavenly bodies orbited around the Earth.

PAUL
This view of the world is called the geocentric model.

RACHEL
The geocentric model made sense because no one figure out how moons can remain in orbit around a planet while the planet is orbiting the sun.

PAUL
It also helped that no one felt Earth move or spin.

RACHEL
Galileo’s observations of the four large moons orbiting Jupiter showed that it was indeed possible to have more than one center of motion in the universe.

PAUL
That observation, along with his later observation of the phases of Venus cleared the way for astronomers to accept a new model for the solar system.

RACHEL
Nicholas Copernicus advocated this new model and it placed the sun at the center of the solar system.

PAUL
Although Copernicus did have some competition.

RACHEL
That’s right. Astronomer Tycho Brahe argued for a model that combined both the geocentric and heliocentric models.

PAUL
His mixed model had two benefits. First, it still left Earth stationary at the center of the solar system.

RACHEL
And second, it didn’t require the stars to be fantastically far away.

PAUL
You can see the Galileo’s Jovian satellites yourself with a pair of binoculars.

RACHEL
You’ll need to hold the binoculars steady against something, like a tree.

PAUL
Jupiter rises in the east-northeast at 6:00 PM this week.

RACHEL
You can’t miss it; Jupiter will be the brightest star in the sky.

PAUL
Happy birthday Stephen Hawking.

RACHEL
He celebrates his 74th birthday on the 8th.

RACHEL
That’s Idaho Skies for the second week of January. Next week is the birthday of the man most responsible for the Space Race of the 1960s. 

PAUL
Be sure to read our blog for additional information. It’s at idahoskies.blogspot.com. For Idaho Skies this is Paul…

RACHEL
...and Rachel.

PAUL
Dark skies and bright stars.