Tuesday, July 11, 2017

Idaho Skies Star Charts for July

Don't confuse Jupiter for Spica. Jupiter will be brighter and more yellowish. Aim your binoculars at Jupiter to see its largest satellites. They will change their position relative to Jupiter nightly. Steady your binoculars for better views. A tree, fence post, or car make good props.

Jupiter's second largest satellite will be the easiest to see through binoculars. The others are a little too close to the glare of Jupiter on the 1st.

Zubenelgenubi is a widely spaced double star. Most people can split it into two with binoculars.

Ptolemy's Cluster was identified as a fuzzy spot nearly 2,000 years ago. Through binoculars, it changes from a fuzzy cloud and into a cluster of stars.

The moon sits between Earth and the center of the Milky Way galaxy on the 7th. This means you'll find lots of star clusters and nebulas surrounding the moon. Use your binoculars.

Mercury makes a poor appearance in July. Your best days to see this tiny planet are around the 13th.

The Morning Star passes along side two attractive star clusters this month. Watch Venus change its position relative to  the Hyades star cluster this week.

A slightly tough object to find this month because binoculars have a field of view of 7.5 degrees. Try finding Uranus by placing the center of the moon at the 7 o'clock position of your binoculars. Uranus will be the second brightest star near the 1 o'clock position. 

There's a tight pairing between the thin crescent moon and Venus on the morning of the 20th.

The sky will still be illuminated by the setting sun when Mercury, Regulus, and the moon group up. Use binoculars, but only after the sun has set, to find this attractive trio. Mercury is brighter than Regulus,  the brightest star in Leo the Lion.    

The second time the moon passes close to Jupiter is on the 28th. Be sure to use your binoculars to scan the moon and Jupiter.

Binoculars will show you Ganymede and Callisto on the 28th. 

Idaho Skies Transcript for July 28th to 30th

RACHEL
Welcome to Idaho Skies for July 28th, 29th, and 30th. We’re your hosts, Rachel...


PAUL
...and Paul.


RACHEL
Stargazers will find the moon keeping excellent company on the evening of the 28th.


PAUL
They are two stars below the moon in the west-southwest.


RACHEL
The brightest star is not actually a star, its Jupiter and it appears to the right of the moon.


PAUL
The fainter of the two stars is Spica and it’s to the left of the moon.


RACHEL
Through binoculars, Spica won’t change its appearance, but will look brighter.


PAUL
Jupiter, on the other hand, does change its appearance through binoculars.


RACHEL
The actual disk of the planet is barely visible through binoculars.


PAUL
The best way to see the disk of Jupiter is observe the planet before the sky is completely dark.


RACHEL
That’s because in total darkness, the glare of Jupiter creates flares radiating beyond the actual disk of the planet.


PAUL
Jupiter’s four largest satellites are also easy to see through binoculars.


RACHEL
Although on the 28th, only two of satellites are visible.


PAUL
Because the other two are too close to the planet.


RACHEL
Farthest from Jupiter is Callisto and it’s to the left of the planet.


PAUL
The other is Ganymede, and it’s between Callisto and Jupiter.


RACHEL
It’s helpful if you steady your binoculars against something stationary, like a fence post.


PAUL
That way, you reduce the shaking of your arms.


RACHEL
And a steady view always makes fainter stars appear brighter in binoculars.


PAUL
That’s Idaho Skies for the 28th, 29th, and 30th of July.


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


PAUL
...and Paul.


RACHEL
Dark skies and bright stars.

Idaho Skies Transcript for July 26th and 27th

PAUL
Welcome to Idaho Skies for July 26th and 27th. We’re your hosts, Paul...


RACHEL
...and Rachel.


PAUL
We take instant communications for granted these days.


RACHEL
Instantaneous communication started to become available after the first trans-Atlantic telegraph cable was completed on August 16th, 1858.


PAUL
Unfortunately, the first message over undersea telegraph took 17 hours to complete.


RACHEL
Which is still a big improvement from the ten days it took the fastest ships to sail across the Atlantic.


PAUL
The next improvement to rapid global communications occurred when the radio was invented by Marconi in the early 20th century.


RACHEL
But the greatest improvement of all began on July 26th, 1963.


PAUL
That’s when NASA launched Syncom 2, the first geosynchronous communication satellite.


RACHEL
Being positioned in geosynchrous orbit meant it orbited Earth once every 24 hours.


PAUL
But geosynchrous is n0t the same thing as geostationary.


RACHEL
Wait, what?


PAUL
Yep, even though it orbited Earth once a day, the satellite was placed in an orbit inclined to the equator.


RACHEL
Oh I see. So it didn’t remain over the same spot over the equator.


PAUL
That’s right. It drifted north and south, but maintained a fixed path over the Earth.


RACHEL
So at least a satellite dish didn’t need to move very much in order to track Syncom 2.


PAUL
Still, it opened up high speed and dependable communications cross the globe.


RACHEL
Yep. In fact, the first communications over satellite between heads of state took place through Syncom 2.


PAUL
That’s Idaho Skies for the 26th and 27th of July.


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.

Idaho Skies Transcript for July 24th and 25th

RACHEL
Welcome to Idaho Skies for July 24th and 25th. We’re your hosts, Rachel...


PAUL
...and Paul.


RACHEL
The three day old moon appears as a very thin crescent in the low west at 10:00 PM on the 25th.


PAUL
The good news is that Mercury and Regulus accompany the moon.


RACHEL
The bad news is that both will be difficult to see on account of their closeness to the still, well-lit horizon.


PAUL
Therefore, stargazers will find a pair of binoculars very helpful in locating these astronomical objects.


RACHEL
Just be sure you don’t begin scanning the horizon until after the sun has set.


PAUL
Regulus, which is the brightest star of Leo the Lion, appears slightly fainter than Mercury.


RACHEL
So if you have difficulty finding Regulus, look for a slightly faint star just below and left of Mercury.


PAUL
Did you know that Mercury is only 1/3rd the distance from the sun than as Earth?


RACHEL
That means the solar gravity tugging on Mercury is nine times greater than it is on Earth.


PAUL
Because of this increased gravitational strength, Mercury must obit the sun in 88 days to avoid falling into it.


RACHEL
So Mercury’s year lasts only 1/6th as long as a year on Earth.


PAUL
Its closeness to the sun also means that the sun’s light is nine times more intense at Mercury.


RACHEL
It means spacecraft exploring Mercury need heat shields just to withstand the sun’s heat.


PAUL
So I guess if you can’t stand the heat, get out of Mercury’s orbit.


RACHEL
Um, yeah. That reminds me, it’s your turn to make dinner this week.


PAUL
That’s Idaho Skies for the 24th and 25th of July.


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


PAUL
...and Paul.


RACHEL
Dark skies and bright stars.

Idaho Skies Transcript for July 21st to 23rd

PAUL
Welcome to Idaho Skies for July 21st, 22nd, and 23rd. We’re your hosts, Paul...


RACHEL
...and Rachel.


PAUL
The moon turns new on the 23rd.


RACHEL
It’s just one more lunar month before the total solar eclipse that will grace Idaho skies in August.


PAUL
This month, the moon passes five degrees south of the moon.


RACHEL
So it’s not creeping closer and closer to the sun each month as we approach August’s solar eclipse.


PAUL
If you haven’t yet, get your solar viewing filter now.


RACHEL
Remember that you can never look at the sun without eye protection.


PAUL
The only time you can safely look at the sun is during the totality phase of a solar eclipse.


RACHEL
Because during totality, the moon completely obscures the sun’s light.


PAUL
In place of the sun’s photosphere, or bright outer shell, you’ll see million-degree plasma streaming away from the sun.


RACHEL
The appearance of the corona is strongly affected by the sun’s magnetic field.


PAUL
Therefore, we won’t know the exact shape of the sun’s corona until the time of the eclipse.


RACHEL
If you can’t get a solar filter in time, there’s a chance local libraries will have some available.


PAUL
Astronomers are hoping to get images of the solar corona all throughout the eclipse’s path across the United States.


RACHEL
That way they can combine these images together into a movie.


PAUL
Then we’ll see how the shape and size of the corona changes minute by minute for over an hour.


RACHEL
That’s Idaho Skies for the 21st, 22nd, and 23rd of July.


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


RACHEL
...and Rachel.


PAUL
Dark skies and bright stars.

Idaho Skies Transcript for July 19th and 20th


RACHEL
Welcome to Idaho Skies for July 19th and 20th. We’re your hosts, Rachel...


PAUL
...and Paul.


RACHEL
Early birds going outside at 4:30 AM on the 20th will find the Morning Star just a tiny bit above a very thin crescent moon.


PAUL
Together, they’ll make a scene worth getting your binoculars out.


RACHEL
But wait, there’s more!


PAUL
That’s right. Aldebaran will be the star to the right of Venus and the moon.


RACHEL
Stargazers will notice a big difference between the colors of Venus and the star Aldebaran.


PAUL
Venus is a steadfast bright white star while Aldebaran is a twinkling paler yellowish star.


RACHEL
Let’s talk about Aldebaran for a moment.


PAUL
Sure. Aldebaran is the 10th brightest star that we can see from Idaho.


RACHEL
It’s only 50% heavier than the sun, but 44 times larger in size.


PAUL
In Arabic, Aldebaran means the follower.


RACHEL
It probably has that name because it follows the Pleiades.


PAUL
It’s 65 light years away, so the light you see tonight left in 1952.


RACHEL
Did you known that that Aldebaran plays a part in Joe Haldeman’s novel, The Forever War?


PAUL
Yes I did. In his book, humans are fighting a race of aliens from around Aldebaran.


RACHEL
Well, did you know that Earth has launched a spacecraft to Aldebaran?


PAUL
Well, actually, NASA launched a spacecraft to explore Jupiter in 1971 and now it’s escaped the solar system.


RACHEL
That spacecraft, Pioneer 10 will sail past Aldebaran in roughly two million years.


PAUL
Of course, it will be a dead and probably battered spacecraft by the time it arrives.


RACHEL
That’s Idaho Skies for the 19th and 20th of July.


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


RACHEL
...and Rachel.


PAUL
Dark skies and bright stars.

Idaho Skies Transcript for July 17th to 18th

PAUL
Welcome to Idaho Skies for July 17th and 18th. We’re your hosts, Paul...


RACHEL
...and Rachel.


PAUL
Here’s a slightly difficult observation for stargazers.


RACHEL
Try to find Uranus on the 17th.


PAUL
It’s more difficult than usual because the planet is seven degrees away from the moon that night.


RACHEL
Recall that most binoculars have a field of view of 7.5 degrees.


PAUL
So go outside at 4:30 AM on the 17th and place the center of the moon at the 7 o’clock position of your binoculars.


RACHEL
Uranus will appear at the opposite edge or at the 1 o’clock position.


PAUL
Watch out though, there’s a star slightly brighter than Uranus near the same position.


RACHEL
However, this star is a little to the lower right of Uranus.


PAUL
When you locate Uranus, you’re looking at a planet four times larger than Earth and 1.85 billion miles away.


RACHEL
1.85 billion miles is 20 times farther away from the sun than Earth.


PAUL
And that makes the sun’s gravity 400 times weaker at Uranus than at Earth.


RACHEL
That weaker pull of gravity means Uranus doesn’t have to travel quite so fast to balance the sun’s pull.


PAUL
That’s why its year or time it takes to go around the sun lasts 85 years.


RACHEL
Before finishing, take a moment to look at the moon.


PAUL
It’s approaching one lunar month old, so it’s a thin crescent.


RACHEL
So if you leave early to work, be sure to start looking for earthshine on the moon.


PAUL
It appears as the faint illumination on the upper right side of the moon.


RACHEL
That’s Idaho Skies for the 17th and 18th of July.


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


RACHEL
...and Rachel.


PAUL
Dark skies and bright stars.