Transcript for July 17th to 23rd

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

PAUL
...and Paul.

RACHEL
The nearly full moon is surrounded by star clusters and nebulae on the 17th.

PAUL
Many of them are visible in binoculars as fuzzy spots and small knots of stars.

RACHEL
The star clusters and nebulae are located in the thickest part of the Milky Way.

PAUL
And that means it’s towards the center of our galaxy.

RACHEL
To see these star clusters and nebulae, scan the sky around the moon with binoculars.

PAUL
Remember that it’s easier to see the star clusters and nebulae if you move the moon out of your binocular’s field of view.

RACHEL
Why are these nebulae glowing with their own light?

PAUL
Well, there are two reasons nebulae glow.

RACHEL
The one case, some nebulae are located next to bright stars.

PAUL
The starlight reflects off of the dust filling the nebulae.

RACHEL
In long duration photographs, these nebulae are bluish-white in color.

PAUL
Astronomers call these nebulae reflection nebulae.

RACHEL
And the other kind of nebulae?

PAUL
Young and very hot stars are embedded in these kinds of nebulae.

RACHEL
Since the stars are hot, they emit lots of ultraviolet radiation.

PAUL
The ultraviolet makes the low pressure gas inside the nebulae glow like a fluorescent light or black light poster.

RACHEL
Astronomers call this emission nebula.

PAUL
And in astronomical photographs, these nebula appear red in color.

RACHEL
One of the most famous reflection nebulae is the glowing cloud of dust surrounding the Pleiades.

PAUL
Arguably, the most famous emission nebulae is the Orion Nebula.

RACHEL
Funny thing though, it appears green through an amateur telescope.

PAUL
Green? Why green?

RACHEL
There’s lots of red glowing hydrogen inside the Orion nebula, but our eyes are not very sensitive to red.

PAUL
The green comes from less abundant oxygen atoms that have lost two electrons.

RACHEL
Our eyes are much more sensitive to color green than to red.

PAUL
So even through there’s more hydrogen in the Orion Nebula, the green glow from oxygen overwhelms the red glow of hydrogen.

RACHEL
The moon is full on the 19th.

PAUL
The full moon in July is called the Thunder Moon.

RACHEL
Thunder moon? Why?

PAUL
Probably because in the eastern US, thunderstorms are more prevalent during this time of year.

RACHEL
Doesn’t each full moon have a name?

PAUL
Yes they do. Different cultures give the full moons different names.

RACHEL
So which moth has a full moon called the Blue Moon?

PAUL
None, really.

RACHEL
What?

PAUL
Yep. In one definition, the Blue Moon is the second full moon within any month.

RACHEL
There’s another definition?

PAUL
Yes there is, but we’re out of time.

RACHEL
So we’ll have to discuss this further next week.

PAUL
That’s Idaho Skies for the third week of July. See if you can find the outer planets next 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.