Transcript for March 6th to 12th

RACHEL
Welcome to Idaho Skies for the first week of March. We’re your hosts, Rachel...

PAUL
...and Paul.

RACHEL
Jupiter reaches opposition on the 8th.

PAUL
Opposition? What does that mean?

RACHEL
It means that Jupiter is located opposite the sun in our sky.

PAUL
Oh, and therefore at it’s closest to Earth for the year.

RACHEL
And it’s slightly brighter and larger than usual for the next few weeks.

PAUL
Jupiter rises in the east by 6:30, which is before the sky even gets dark.

RACHEL
Binoculars will let you see several of its large satellites, which we also call the Galilean Satellites.

PAUL
They’re named the Galilean Satellites because Galileo discovered them with his new telescope.

RACHEL
This occurred between December 1609 and January 1610.

PAUL
Galileo was not the first person to turn the newly invented telescope heavenward, but he was the first to make systematic records of his observations.

RACHEL
Galileo was a committed Copernican, or supporter of the hypothesis put forth by Polish astronomer Nicholas Copernicus.

PAUL
Without having the evidence to back him up, Copernicus proposed that the sun was the center of the solar system and not Earth.

RACHEL
This concept actually goes back to the ancient Greeks.

PAUL
To Copernicus and others, placing the sun at the center of the universe seemed to make the planetary motions easier to understand.

RACHEL
Especially the retrograde motion of planets like Mars.

PAUL
So just what is retrograde motion?

RACHEL
Retrograde is when planets like Mars moved from east to west or backwards from their normal direction of travel across the sky.

PAUL
The accepted explanation was that the planets orbited Earth in deferents and epicycles.

RACHEL
This is a model of motion where planets travel in circles inside of other circles that are orbiting Earth.

PAUL
As the circles rotated at their own particular rate, they sometimes made a planet speed up, slow down, or even move backwards for a brief period of time.

RACHEL
One argument used against Copernicus’ hypothesis of the sun-centered universe is that the moon couldn’t orbit around Earth if Earth was orbiting around the sun.

PAUL
Otherwise, Earth would leave the moon behind.

RACHEL
Galileo’s observations of satellites orbiting Jupiter proved that satellites could orbit a planet while the planet orbited another body, be it the sun or Earth.

PAUL
So when you see the Galilean Satellites on the night of the 8th, remember that they’re orbiting a giant planet traveling at 29,000 miles per hour.

RACHEL
Speaking of moons...

PAUL
...the moon is just over 2 days old on the 10th.

RACHEL
That night however, the very thin crescent moon keeps very distant company, Uranus.

PAUL
The planet Uranus is 2 degrees or four apparent lunar diameters away from the moon.

RACHEL
To see Uranus, aim your binoculars at the thin moon, which is in the low west at 8:00 PM on the 10th.

PAUL
Then shift your binoculars to place the moon at the 8:00 o’clock position of your binoculars field of view.

RACHEL
This is also the lower left edge of the field of view.

PAUL
The star near the center of the binoculars field of view will be Uranus.

RACHEL
Uranus is easy to see in binoculars, but having the moon nearby makes finding it a whole lot easier to find.

PAUL
That’s Idaho Skies for the first week of March. Next week is star cluster week.

RACHEL
Be sure to follow us on Twitter at Idaho Skies for this week’s event reminders and sky maps.

For Idaho Skies this is Rachel...

PAUL
...and Paul.

RACHEL
Dark skies and bright stars.