Transcript for April 17th to 23rd

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

PAUL
...and Paul.

RACHEL
You’ll find a bright yellow-white star 3 degrees above the moon on the night of the 17th.

PAUL
That bright star is actually a planet, the planet Jupiter.

RACHEL
It’s also the largest planet in the solar system.

PAUL
In fact, it's about 11 times larger than Earth.

RACHEL
Through your binoculars, you can see three of its largest satellites after it gets dark at around 10:00 PM.

PAUL
However, if you observe again at 11:00 PM, you’ll see four satellites.

RACHEL
Wait, another satellite in less than an hour?

PAUL
Yep. That’s because its giant satellite Ganymede is traveling out of Jupiter’s shadow.

RACHEL
If you look closely at the left side of Jupiter, or toward our east, Ganymede will gradually grow brighter as 11:00 PM approaches.

PAUL
Remember that telescopes invert objects, so if you observe this event through a telescope, then Ganymede will reappear from the right side of Jupiter.

RACHEL
Mercury reaches its greatest eastern elongation on the 19th.

PAUL
Elongations are only possible for inferior planets or those planets closer to the sun than Earth.

RACHEL
That’s Mercury and Venus.

PAUL
That’s right. Elongations occur when the position of an inferior planet places it at its greatest distance from the sun, with respect to Earth.

RACHEL
That’s important because it’s when inferior planets appear at their greatest distance from the sun.

PAUL
Therefore, we see them for longer periods of time and in darker skies.

RACHEL
Your best view of tiny Mercury takes place on the evening of the 19th.

PAUL
Plan to be outside at 9:30 and look for the planet in the low west-northwest.

RACHEL
The first reasonably bright white star you see that’s a little above the horizon is Mercury.

PAUL
Be sure to check up on Mercury over the next few days.

RACHEL
That’s because you’ll notice that it’s getting closer to the horizon each night.

PAUL
And by the 28th, the planet wil be too close to the horizon for you to see.

RACHEL
The Lyrid meteor shower reaches its peak intensity on the night of the 21st and morning of the 22nd.

PAUL
Lyrid meteors appear to originate near the star Vega, the bright star you’ll see in the low east-northeast after 10:00 PM.

RACHEL
In good dark skies, one can see upwards of 15 meteors per hour from this shower.

PAUL
Even better, some of them are exceptionally bright and create lingering trails.

RACHEL
Unfortunately, the moon is full that night and its light will wash the sky clean of the fainter meteors in this shower.

PAUL
However, it still may be worth observing this shower for a while because of its brightest members.

RACHEL
When you see a Lyrid streak across the sky, you’re witnessing the destruction of a grain of dust from a long dead comet.

PAUL
The dust grains begin vaporizing at altitudes between 60 and 80 miles.

RACHEL
While most meteoroids are only the size of a pinhead, we can see them from hundreds of miles away.

PAUL
The reason is because Lyrid meteoroids enter Earth’s atmosphere at speeds of around 29 miles per second.

RACHEL
And that’s a lot of kinetic energy to dissipate.

PAUL
That’s Idaho Skies for the third week of April. The planets Mars and Saturn are easy to locate 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.