Monday, May 2, 2016

Idaho Skies for May 2016



May 1 – 7

The moon is new on the 6th, but on the mornings of the 2nd and 3rd, it’s visible in the low east before sunrise. If you leave for work before sunrise, be sure to take a look at the moon and Earthshine on its right side. You’ll need to make this observation by around 4:45 AM. Much later and the light of dawn will wash out Earthshine.



The Eta Aquarid meteor shower peaks on the night of the 6th and morning of the 7th, which is awesome since this is a Friday night and Saturday morning. We can observe up to 30 meteors per hour from this shower; unfortunately, this is the case if you live the southern hemisphere. However, it’s still worth observing this shower as the nights are getting warmer and the moon is new. That means we’ll have warm, dark skies for observing this shower. There’s no need to watch this shower all night, as the radiant for the shower doesn’t rise until after 3:00 AM. So look for meteors appearing from the low east after 3:00 AM.  


 May 8 – 14
The moon reappears in the low west-northwest on the 8th. So after it gets dark after 10:00 PM, look for the moon and see if you can detect Earthshine illuminating its dark portion. Earthshine will be most visible if you view the moon through binoculars. The brightish orange star to the left of the moon is Betelgeuse, a star in the shoulder of Orion. You can make observations of Earthshine for several more nights.


Mercury made an evening appearance last month, but disappeared before the end of April. This month Mercury passes between Earth and the sun and in Idaho, we get to see a part of that. This is called a transit and it only happens on an average of 13 times per century. The transit begins on the 9th at around 7:00 AM in Idaho and ends shortly after noon.


A transit is not safe to observe directly with your eyes, since it requires looking at the sun. This means that a telescope properly covered with solar viewing filters can observe the transit of Mercury, but other instruments cannot. The rest of us will need to rely having an acquaintance who is an amateur astronomer, finding a local astronomy club giving public viewings, or using the projection method of observing the sun. How can you project an image of the sun? A pair of binoculars, spotting scope, or small telescope pointed at the sun will project an image of the sun out its eyepiece. Do NOT look at this image through the eyepiece. Instead, position the telescope so that the image projecting out of the eyepiece falls upon a sheet of paper. Then focus the binoculars, spotting scope, or telescope so that the image is sharp. Any sunspots visible during the transit will appear to have fuzzy edges while Mercury will be a tiny round dot with well-defined edges. Mercury will transit south of the sun’s equator, from Earth’s perspective. Remember that if you observe the transit with a telescope, the image will be upside down.   

Gemini appears like the waist and legs of a soccer player. Look in the low west after dark in May and you’ll see upright Gemini as two columns of stars. At the top of the columns are two bright stars, Pollux (on the left) and Castor (on the right). Castor and Pollux mark the head of the Gemini Twins, but more like the waist of a soccer player. Even better, on the evening of the 9th, the crescent moon appears at the feet of Gemini just like Gemini is about to kick it like a soccer ball.


One of the closest stars to the sun appears to the lower left of the moon on the 10th. The star’s name is Procyon, which means “Before the Dog”. The dog in this case is the Dog Star, Sirius. Procyon gets this name because it rises shortly before the rising of Sirius. Procyon is the eighth brightest star in the sky because it’s only 11.5 light years away and not because its particular bright compared to other stars. Procyon is a young star, only one quarter the age of the sun. Procyon is the brighter of the two stars forming the constellation of Canis Minor, or the Little Dog.      


Hey, want to see a really nice star cluster? You can on almost any night, but the 11th is better because the moon will help you find it. The star cluster is named the Beehive Star Cluster and you’ll find it 7 degrees above the moon on the night of the 11th. To see this attractive star cluster, point you binoculars at the moon and then tilt them directly north of the moon. Just after the moon leaves the binoculars’ view, the Beehive will appear at the top of the field of view. You should see a striking similarity between the Beehive and a swarm of bees.


The moon reaches the first quarter phase on the 13th. The star Regulus also appears above the moon that night. Regulus is the brightest star of Leo the Lion. The constellation is standing on end above the moon that night. Regulus is so close to the moon that both can be seen together at the same time through binoculars.


There’s an even brighter star above the moon on the night of the 14th. In his case, the star is Jupiter, the King of the solar system’s planets. Both the moon and Jupiter can be seen together in your binoculars on the 14th. You should notice that Jupiter appears as a more intense source of light than the moon and that it is accompanied by a retinue of satellites. On the 14th, binoculars will let you see up to three of Jupiter’s moons. From left to right, the moons will be Callisto, Europa, Jupiter, and Ganymede. The planet’s innermost moon Io very close to Jupiter and might not be visible through binoculars. If you have a spotting scope or larger, then Io appears near the right edge of Jupiter.

May 15 – 21

The moon passes very close to Spica on the night of the 17th. Spica is the brightest star of Virgo the Maiden, the second largest constellation. Virgo is made up of dim stars, so the constellation doesn’t stand out to the extent its large size should make it. One depiction of Virgo is as a goddess of justice named Justitia. In this guise, she holds the scales of justice in her hands, or the constellation of Libra.   

A widely spaced double star located in Libra can be found below the moon on the 19th. The star’s name is Zubenelgenubi and the angular distance between the companion stars is wide enough that some people can see it as two separate stars without optical aid. The rest of us need a pair of binoculars. The star is 5 degrees below the moon, therefore, place the moon at the top of your binocular’s view and Zubenelgenubi will be the bright pair of stars at the bottom.


The moon is full on the 21st. Full moons in May are sometimes called the Flower Moon and you’ll find the Flower moon located between the planets Mars and Saturn. Mars will be the bright orange-tinted star to the right of the moon and Saturn will be the fainter yellow-white star to the lower left of the moon. Below the moon is another orange star, Antares. Antares is the heart of Scorpius the Scorpion.

May 22 – 30

Mars reaches opposition on the 22nd. At opposition, superior planets, or those beyond Earth, are at their closest to Earth for the year. Opposition occurs when the faster orbital motion of Earth results in Earth catching up to and passing the superior planet in question. In the process of reaching opposition, superior planets appear to retrograde, or move slightly backwards across the stars. Retrograde motion is an illusion caused by the changing perspective between Earth and superior planets when compared to the fixed stars. Hundreds of years ago, when the geocentric or Earth-centered solar system was in vogue, astronomers and philosophers believed the superior planets actually moved backwards during a short period of time. This was possible because these planets orbited Earth in a set of nested orbits of various sizes. Copernicus convinced astronomers in the 16th century that the retrograde motion of the planets was easier to explain by moving the sun to the center of the solar system and demoting Earth to a planet orbiting the sun.   


The bright yellowish star visible to the right of the moon on the 22nd is Saturn. You’ll need at least a spotting scope capable of magnifying at least 25 times in order to see the planet’s rings and largest satellite, Titan. Titan is a fascinating world. It’s larger than Earth’s moon and surrounded by an atmosphere denser than Earth’s. Unfortunately, it’s intensely cold on Titan. So cold that methane, a gas used to heat our homes, is a liquid. Its nitrogen-rich atmosphere is almost cold enough to liquefy. Because of its dense atmosphere and liquid methane, Titan has weather, but probably not as dynamic as Earth’s. This still allows it to rain on Titan, but with methane rain.   

If you’re a late night person, you can use the moon to locate several star clusters and nebulae on the morning of the 24th. These attractive deep sky objects are located between Earth and the center of our galaxy, meaning they appear in the thick of the Milky Way (which is why you need to wait until after midnight to see them). These clusters and nebulae are small, so you need a pair of binoculars to see them. Through binoculars, the nebulae will appear as fuzzy spots while the star clusters will have some stars sprinkled among the fuzz.  
  

The moon is last quarter on the 29th, which is nice, but it has a neighbor that night that will give you a real astronomy challenge. The eighth planet, Neptune is just 4.5 degrees away from the moon on the 29th. This means you can see both together in a pair of binoculars, which typically have a field of view of 5 degrees. You need dark skies in order to see Neptune, so leave town for the countryside. To see Neptune, place the moon on the right edge of your binoculars and find the brightest star directly east of the moon. This star will be near the left edge of your binoculars. A small distance farther east of the bright star is a faint star that’s as bright as Neptune. The distance between the star and the brighter star is the same distance Neptune is away from the bright star. Neptune is the other faint star down and slightly left of the bright star. The bright star, faint star, and Neptune will form a small triangle with a 90 degree apex.    


The moon is close to the eastern horizon as you drive to work on the 31st. Can you see Earthshine? Binoculars will definitely help (but don’t use binoculars while you drive!).



This Month’s Sources

Astronomical Phenomena of the Year 2016, The Nautical Almanac Office and Her Majesty’s Nautical Almanac Office
Astronomy Calendar of Celestial Events for Calendar Year 2016, http://www.seasky.org/astronomy/astronomy-calender-2016.html
Climate of Titan, https://en.wikipedia.org/wiki/Climate_of_Titan
Mercury Transits the Sun, http://skyandtelescope.com/observing/ceelstial-objects-to-watch/mercury-transits-thesun/
Night Sky Explorer
Virgo, https://en.wikipedia.org/wiki/Virgo_(constellation)

Transcript for May 1st to 7th

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

PAUL
…and Paul.

RACHEL
The moon is new on the 6th.

PAUL
That means it’s been approaching closer to the sun for the last two weeks.

RACHEL
When the moon is approaching the sun, its phase gets smaller.

PAUL
Or more crescent shaped

RACHEL
And this means the far side of the moon is becoming more illuminated.

PAUL
When the moon’s phase gets smaller each day, we call it a waning moon.

RACHEL
That’s the opposite of when the moon is getting farther from the sun each day.

PAUL
Then the moon’s phase gets larger each day.

RACHEL
And we call this a waxing moon.

PAUL
Because the moon is new on the 6th, the waning crescent moon is visible in the low east before sunrise on the 2nd and 3rd.

RACHEL
If you leave for work before sunrise on those days, then take the opportunity to look at the moon and Earthshine illuminating its right side.

PAUL
You’ll need to make this observation by around 4:45 AM.

RACHEL
Because much later and the light of dawn will wash out Earthshine.
PAUL
The Eta Aquarid meteor shower peaks on the night of the 6th and morning of the 7th.

RACHEL
That’s awesome since that’s a Friday night and Saturday morning.

PAUL
This shower produces up to 30 meteors per hour in dark skies.

RACHEL
Unfortunately, you live in Idaho.

PAUL
And Aquarius is a constellation located south of he equator.

RACHEL
And since you’re an inhabitant of the Northern hemisphere, you’ll see fewer meteors per hour.

PAUL
However, it’s still worth observing this shower.

RACHEL
That’s because the nights are getting warmer and the moon is new.

PAUL
So you’ll have more comfortable nights and darker skies.

RACHEL
There’s no need to watch this shower all night, however.

PAUL
Because the radiant point of this shower doesn’t rise until after 3:00 AM.

RACHEL
All Eta Aquarid meteors will appear to originate from a point in the sky located in the low east.

PAUL
This point is called the meteor shower’s radiant.

RACHEL
The radiant’s exact position depends on when the meteor stream intersects Earth’s orbit.

PAUL
And the constellation in which the radiant occurs is usually the meteor shower’s name.

RACHEL
There’s more than one meteor shower that originates in the constellation of Aquarius, so the Eta Aquarids are also given the name of the star they originate near.

PAUL
Be sure to appreciate each meteor you see.

RACHEL
That’s because each meteor streaking across the sky is vaporizing from the heat of its entry into Earth’s atmosphere.

PAUL
And as a result, each glowing meteor is giving up its existence in order for you to enjoy it.

RACHEL
So sad.

PAUL
That’s Idaho Skies for the first week of May. Next week the planet Mercury crosses the face of the sun.

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.

This Month's Star is Mizar

This month look for the star Mizar and its companion star Alcor. Mizar is the star located in the bend of the handle of the Big Dipper. Look carefully at this star and you’ll probably detect its faint companion star, Alcor. Use your binoculars if you’re not certain that you can see this fainter star. The position of Alcor, relative the Mizar places it at an angle pointing away from the bend in the Dipper’s handle. I get the impression that the distance between the two stars is the same as 1/8th of an inch appears when viewed at arm’s distance. It may be hard to believe, but Mizar and Alcor have an angular separation close to half the diameter of the moon. When you look at Mizar with even slight optical aid, you’ll notice something else; it’s a double star (so there are three stars visible in a telescope).

Mizar was the first double star astronomers discovered (in 1650). Mizar is over twice as massive as our sun and Alcor is over 50% heavier than our sun. The pair is between 78 and 81 light years from the earth (the distance is uncertain). The actual distance between Mizar and Alcor may be anywhere between 1/4 to over 3 light years. So it’s possible that these two stars are not actually in orbit around each other. However, if they are in orbit around each other, their orbital period may be in the hundreds of thousands of years!     

Tuesday, April 26, 2016

The Street Astronomer’s Guide to Idaho Astronomical Resources

Easy Star Gazing
The Street Astronomer holds Easy Star Gazing presentations at several locations in the Treasure Valley during March, June, September, and December.

Easy Star Gazing Notes
An online copy of the Easy Star Gazing class and links is available at nearsys.com/easy

Idaho Skies Radio Program
Radio Boise (89.9 FM Caldwell/Boise and 93.5 FM Garden City) presents a regularly scheduled astronomy program at the following times
Tuesday at 3:30 PM
Wednesday at 3:30 PM
Thursday at 7:30 PM
Friday at 10:30 AM and 10:30 PM
Sunday at 8:30 PM
 
Follow Idaho Skies tweets at www.twitter.com/Idahoskies

The Idaho Skies blog is located at http://idahoskies.blogspot.com

Monthly Star Maps
Free stars maps are available online at http://www.skymaps.com/downloads.html
(Click the Northern Hemisphere PDF file in the left column

Idaho Astronomy Clubs
Boise Astronomical Society (BAS)
Boise’s astronomy club meets on the second Friday of the month at the Discovery Center of Idaho.  Meetings begin at 7:00 PM, except for July, December, and an annual planetarium meeting which are a members only event. http://www.boiseastro.org

Idaho Falls Astronomical Society (IFAS)
Idaho Falls’ astronomy club meets on the third Tuesday of the month at the Skyline Activity Center, 1575 N. Skyline Dr. Meetings begin at 7:00 PM.
http://www.ifastro.org/

Magic Valley Astronomical Society (MVAS)
Twin Falls’ astronomy club meets on the second Saturday of the month at the Herrett Center, College of southern Idaho.  Meetings begin at 7:00 PM and are followed by a public star party upstairs. http://www.mvastro.org

Palouse Astronomical Society (PAS)
Northern Idaho’s astronomy club meets the first Thursday of the month. Locations change, so consult their calendar at, http://palouseastro.org/

Idaho Observatories
Bruneau Dunes Observatory
Idaho’s largest public observatory is located at the Bruneau Dunes State Park. The observatory is open from early April to Mid October. Observatory sessions are preceded by a presentation in the Steele Reese Center. http://parksandrecreation.idaho.gov/parks/bruneau-dunes

BYU-Idaho Observatory
The campus generally opens its observatory on Monday, Tuesday, and Thursday from 7:00 PM to 10:00PM (weather and school schedules permitting). http://www.byui.edu/physics/resources/non-majors/observatory

Centennial Observatory
The observatory at the College of Southern Idaho is open for free star parties one hour after sunset (weather permitting) on the second Saturday of the month and on the second and fourth Tuesdays of the month from November through February. http://herrett.csi.edu/astronomy/observatory/index.asp

Planetariums
BYU-Idaho Planetarium
Weekly planetarium shows are presented on campus in Rexburg every Thursday (school schedule permitting). The door opens at 6:30 PM and the presentation begins at 7:00 PM. The planetarium is located in the Romney Science Building, room 107. http://www.byui.edu/planetarium

Faulkner Planetarium
The Faulkner Planetarium is the largest planetarium in Idaho. Shows are presented Tuesday through Saturday in the summer and Tuesday, Friday, and Saturday the rest of the year. In addition, the planetarium hosts astronomy talks on Fridays in odd months. The planetarium is located at the Herrett Center at the College of Southern Idaho, Twin Falls. http://herrett.csi.edu/astronomy/planetarium/index.asp

Whittenberger Planetarium
The College of Idaho planetarium is opened to the public the first and third Wednesday of the month, school calendar permitting. The door opens at 6:45 PM and the show begins at 7:00 PM. The college is located in Caldwell.  http://www.collegeofidaho.edu/planetarium

Star Parties
Craters of the Moon Star Party
The Magic Valley and Idaho Falls Astronomical Societies jointly hosts an annual star party at the Craters of the Moon National Monument every summer. Consult their webpages for the schedule.  

Idaho Star Party
The Boise Astronomical Society hosts an annual public star party every later summer at Bruneau Dunes State Park. An admission fee is charged for the star party and it is opened to the public. Check the Boise Astronomical Society’s webpage for the schedule.

Monday, April 25, 2016

Transcript for April 24th to 30th

PAUL
Welcome to Idaho Skies for the fourth week of April. We’re your hosts, Paul...

RACHEL
...and Rachel.

PAUL
Are you looking for Mars and Saturn?

RACHEL
You’ll find the red and ringed planets below the moon on the night of the 25th.

PAUL
Mars, appearing as a relatively bright orangish-red star, is located to the lower right of the moon.

RACHEL
Saturn appears as a creamy-white star and it’s located to the lower left of the moon.

PAUL
Don’t confuse Mars for Antares, however.

RACHEL
Mars is a planet while Antares is a red supergiant star.

PAUL
Mars and Antares have similar colors, but you’ll find Antares farther below Mars.

RACHEL
And Antares will be slightly fainter than Mars.

PAUL
Antares represents the heart of the constellation of Scorpius the Scorpion.

RACHEL
It’s a red supergiant, meaning it’s nearing the end of its life.

PAUL
Its core is filled with the helium formed by the hydrogen fuel it consumed during its stellar youth.

RACHEL
The pressure in the core of Antares is so high that the star is fusing this helium into heavier elements like carbon and oxygen.

PAUL
And as a result, hydrogen is fusing into helium in a shell surrounding its helium core.

RACHEL
The high temperature inside of Antares’ core has caused its outer layer to expand to an immense size.

PAUL
In fact, if Antares replaced our sun, the star’s surface would lie between the orbits of Mars and Jupiter.

RACHEL
In a few stellar years, Antares will no longer be able to produce enough heat to support its weight.

PAUL
When that occurs, the massive core of the star will collapse so fast that it will leave the outer shell of the star unsupported.

RACHEL
The iron core of the star will rebound slightly as the outer envelope of the star comes crashing down on the core.

PAUL
The result will be a supernova explosion so bright that it will be seen across a large portion of the universe.

RACHEL
And all that will be left of poor Antares is an expanding cloud of hot gas surrounding a neutron star or black hole.

PAUL
Adios muchachos.

RACHEL
On the night of the 25th, the moon passes just above Saturn.

PAUL
Saturn appears golden yellow in color and it will not twinkle like other stars.

RACHEL
Unlike Jupiter, there isn’t anything you can see on Saturn using binoculars.

PAUL
You’ll need at least a small telescope or spotting scope to see its set of rings.

RACHEL
A magnification of at least 25 power is needed.

PAUL
Saturn’s beautiful rings are made up of uncounted numbers of icy snowballs.

RACHEL
Some of these snowballs are larger than a beach ball.

PAUL
The thickness of the rings varies from 33 feet to about one half of a mile.

RACHEL
This means when scaled to a sheet of paper, the rings of Saturn are thinner (than paper).

PAUL
That’s Idaho Skies for the fourth week of April. Next week, early birds can see Earthshine.

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.



Monday, April 18, 2016

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.

Monday, April 11, 2016

Transcript: April 10 - 16

PAUL
Welcome to Idaho Skies for the second week of April. We’re your hosts, Paul...

RACHEL
...and Rachel.

PAUL
The Hyades is a star cluster named after the daughters of Atlas and they are also the sisters of the Pleiades.

RACHEL
The brightest star appearing in the Hyades star cluster is called Aldebaran.

PAUL
However, Aldebaran is not actually a part of the cluster.

RACHEL
That’s right; it’s a foreground star.

PAUL
The Hyades, which is the closest star cluster to the sun is 151 light years away...

RACHEL
...while Aldebaran is only 65 light years away.

PAUL
The moon appears very close to Aldebaran on the evening of the 10th.

RACHEL
The distance between then is so close that you’ll be able to see both the crescent Moon and Aldebaran together in a pair of binoculars.

PAUL
Looking for Gemini the Twins?

RACHEL
On the evening of the 12th, you’ll find the moon at the feet of Gemini.

PAUL
Hey, Gemini and the moon reminds me of a footballer kicking a soccer ball.

RACHEL
But Gemini only resembles the footballer from the waist down.

PAUL
In other words, the Gemini Twins represents the player’s legs and waist.

RACHEL
There are two bright stars at the player’s hips.

PAUL
The star at the top left is Pollux and the star at the top right is slightly fainter Castor.

RACHEL
Speaking of the moon, it reaches first quarter phase on the 13th.

PAUL
That’s the half full phase.

RACHEL
And it means if you want to see the most spectacular views of the moon, it won’t get any better than on the night of the 13th.

PAUL
So get your binoculars out and scan along the edge of the moon.

RACHEL
Some of the best lunar views occur at first quarter because the moon’s terminator, or boundary between day and night, faces directly towards Earth.

PAUL
At the break of lunar day, shadows cast by the sun stretch their longest across the lunar surface.

RACHEL
And since the lunar terminator is turned directly towards Earth, we see the shadows cast by the sun fully stretched out.

PAUL
This means we see the maximum amount of crater and mountain details through telescopes, spotting scopes, and even binoculars.

RACHEL
The next night, or the 14th, the moon passes an attractive star cluster.

PAUL
The star cluster’s name is the Beehive and it’s just five degrees above the moon.

RACHEL
That distance is just right for most binoculars.

PAUL
Meaning if you place the moon at the bottom of the binoculars' field of view, the Beehive will appear just at the top.

RACHEL
However, your best view of the Beehive occurs when you raise the binoculars high enough to get the moon out of the field of view.

PAUL
...and place the Beehive in the center of view.

RACHEL
Now here’s an old astronomy trick for observing the Beehive.

PAUL
Instead of looking directly at it, try looking at it with the edge of your vision.

RACHEL
While the center of your vision is most capable of seeing details...

PAUL
...your peripheral vision is best at detecting faint light.

RACHEL
Astronomers call this method using averted vision.

PAUL
Using averted vision, you should be able to detect even more stars.

RACHEL
That’s Idaho Skies for the second week of April. Next week the Jovian satellite Ganymede comes out of hiding.

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.