PAUL
Welcome to Idaho Skies for the second week of August. We’re your hosts, Paul…
RACHEL
…and Rachel.
PAUL
The night of the 11th and morning of the 12th is the peak of the Perseid meteor shower.
RACHEL
This meteor shower is best viewed after midnight.
PAUL
That’s when Idaho faces directly into the shower.
RACHEL
It’s similar to driving into a snow storm.
PAUL
That’s right. The rate of snowfall appears to be greater when the car’s direction of travel is into the direction that the snow is falling.
RACHEL
Perseid meteors will appear to radiate from the northeast.
PAUL
Plan to spend some time observing meteors because this shower is very dependable.
RACHEL
You may see more than 30 meteors per hour. And many will be bright and may even flare.
PAUL
136 years ago on the 12th, astronomer Asaph Hall detected a small star-like object close to the planet Mars.
RACHEL
It turned out to be a rock eight miles across orbiting the planet.
PAUL
This was the first Martian satellite that astronomers discovered.
RACHEL
Hall named his discovery Deimos, after one of the twin son’s of the god Mars.
PAUL
The name means terror in Latin.
RACHEL
Because of its small mass, a 12 mile per hour sprint is enough to launch your self off the surface of Deimos and into an eternal orbit around Mars.
PAUL
It wasn’t much later before Hall discovered a second satellite of Mars.
RACHEL
Some people were not surprised to discover that Mars had two satellites.
PAUL
This is because they saw that the two satellites around Mars fit a geometric progression between Earth with one satellite and Jupiter with four satellites.
RACHEL
Jonathon Swift makes mention of this in his story of Gulliver’s Travels.
PAUL
Today we know that Jupiter has far more than four satellites and the fact that Mars has two satellites is just a coincidence.
RACHEL
Speaking of moons, a far less terrifying one appears close to Spica and Saturn on the nights of the 11th and 12th respectively.
PAUL
Both objects will be around three degrees from good ol’ Luna on their night of closest approach.
RACHEL
The best time to look for both of these close approaches is between 10:15 and 10:45 PM.
PAUL
The moon reaches the first quarter phase on the 14th.
RACHEL
As always, this is a great phase for observing the moon with your binoculars or telescope.
PAUL
Focus most of your attention on the terminator, or boundary between day and night, for the greatest amount of visible detail.
RACHEL
The waxing gibbous moon is centered in the Milky Way on the night of the 16th.
PAUL
Search the sky all around the moon with your binoculars and you will find star clusters and nebulas, or clouds of glowing gas.
RACHEL
While binoculars are fine for this, a low power telescope with a wide field of view is even better.
PAUL
Mars passes its closest to Pollux, the brightest star in Gemini on the 17th.
RACHEL
If you have the time, you should start your observations of Mars and Pollux one week earlier.
PAUL
You will notice that Pollux appears higher every morning, but that Mars appears to remain nearly stationary with respect to the horizon.
RACHEL
In time, Earth will begin catching up to Mars.
PAUL
Then Mars will begin appearing in the evening sky rather in the morning sky.
RACHEL
That’s Idaho Skies for the second week of August. Next week we’ll tell you about the planetariums in Idaho.
PAUL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com. For Idaho Skies this is Paul…
RACHEL
and Rachel.
PAUL
Dark skies and bright stars.
Sunday, August 11, 2013
Wednesday, August 7, 2013
Transcript for August 4 - 10
RACHEL
Welcome to Idaho Skies for the first week of August. We’re your hosts, Rachel…
PAUL
… and Paul.
RACHEL
Our best views of Mercury occur during the first half of the month.
PAUL
That’s because Mercury reached greatest western elongation back on July 30th.
RACHEL
Greatest western elongation occurs when Mercury or Venus reaches its greatest angle away from the sun in the eastern morning sky.
PAUL
Since it just past greatest elongation, Mercury is now approaching closer to the sun.
RACHEL
However, the sun is rising later each morning.
PAUL
That means Mercury’s distance above the horizon prior to sunrise remains nearly unchanged for several days.
RACHEL
Look for Mercury low in the east-northeast for the next two weeks.
PAUL
The moon is just above the star Aldebaran on the morning of the 1st. Many listeners know Aldebaran as the orange eye of Taurus the Bull.
RACHEL
Their separation is just over two degrees, or four lunar diameters. Use your binoculars for observing this pair.
PAUL
The moon is a waning crescent on the 3rd. This same day, it also makes a close approach to Jupiter.
RACHEL
Jupiter will be obvious as the bright star to the left of the moon. They both will fit within the field of view of your binoculars.
PAUL
On the 4th, the moon passes close to Mars.
RACHEL
Look for them in the low eastern sky in the morning at 5:45 AM.
PAUL
Mars will appear as a yellowish-orange star located to the upper left of the moon.
RACHEL
The very thin crescent moon should display a strong Earthshine.
PAUL
Many people are unfamiliar with Earthshine.
RACHEL
Earthshine is just sunlight reflecting from the moon.
PAUL
However, before the sun’s light reflected off the moon, it first reflected off Earth.
RACHEL
This reflected Earth light faintly illuminates the dark portion of the moon, which is why it is called Earthshine.
PAUL
When you look at the moon, you will see a brightly illuminated crescent surrounding the rest of its faintly illuminated disk.
RACHEL
If you were an astronaut was standing on the Earthshine portion of the moon, it would be dark because the sun had not risen yet.
PAUL
However, overhead would be Earth.
RACHEL
Earth would appear as a nearly full blue-white disk four times larger than the moon appears in our sky and many times brighter.
PAUL
So sunlight reflecting off Earth more brightly illuminates the moon’s surface than the full moon illuminates Earth’s surface.
RACHEL
On the morning of the 8th, Mercury forms a straight line with the stars Castor and Pollux, the brightest stars of Gemini.
PAUL
You’ll need to go outside a little before 6:00 AM and look in the very low east-northeast.
RACHEL
If you go outside much earlier, Mercury will not have risen high enough for you to see.
PAUL
And if you go outside a little after 6:00 AM, the sun will begin brightening the sky too much to see Mercury clearly.
RACHEL
The very thin waxing crescent moon is located five degrees away from Venus on the evening of the 9th.
PAUL
Look low in the west, as the moon is only three days old.
RACHEL
This ought to be an attractive site in your binoculars.
PAUL
That’s Idaho Skies for the first week of August. Next week is one of the year’s best meteor showers.
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.
Welcome to Idaho Skies for the first week of August. We’re your hosts, Rachel…
PAUL
… and Paul.
RACHEL
Our best views of Mercury occur during the first half of the month.
PAUL
That’s because Mercury reached greatest western elongation back on July 30th.
RACHEL
Greatest western elongation occurs when Mercury or Venus reaches its greatest angle away from the sun in the eastern morning sky.
PAUL
Since it just past greatest elongation, Mercury is now approaching closer to the sun.
RACHEL
However, the sun is rising later each morning.
PAUL
That means Mercury’s distance above the horizon prior to sunrise remains nearly unchanged for several days.
RACHEL
Look for Mercury low in the east-northeast for the next two weeks.
PAUL
The moon is just above the star Aldebaran on the morning of the 1st. Many listeners know Aldebaran as the orange eye of Taurus the Bull.
RACHEL
Their separation is just over two degrees, or four lunar diameters. Use your binoculars for observing this pair.
PAUL
The moon is a waning crescent on the 3rd. This same day, it also makes a close approach to Jupiter.
RACHEL
Jupiter will be obvious as the bright star to the left of the moon. They both will fit within the field of view of your binoculars.
PAUL
On the 4th, the moon passes close to Mars.
RACHEL
Look for them in the low eastern sky in the morning at 5:45 AM.
PAUL
Mars will appear as a yellowish-orange star located to the upper left of the moon.
RACHEL
The very thin crescent moon should display a strong Earthshine.
PAUL
Many people are unfamiliar with Earthshine.
RACHEL
Earthshine is just sunlight reflecting from the moon.
PAUL
However, before the sun’s light reflected off the moon, it first reflected off Earth.
RACHEL
This reflected Earth light faintly illuminates the dark portion of the moon, which is why it is called Earthshine.
PAUL
When you look at the moon, you will see a brightly illuminated crescent surrounding the rest of its faintly illuminated disk.
RACHEL
If you were an astronaut was standing on the Earthshine portion of the moon, it would be dark because the sun had not risen yet.
PAUL
However, overhead would be Earth.
RACHEL
Earth would appear as a nearly full blue-white disk four times larger than the moon appears in our sky and many times brighter.
PAUL
So sunlight reflecting off Earth more brightly illuminates the moon’s surface than the full moon illuminates Earth’s surface.
RACHEL
On the morning of the 8th, Mercury forms a straight line with the stars Castor and Pollux, the brightest stars of Gemini.
PAUL
You’ll need to go outside a little before 6:00 AM and look in the very low east-northeast.
RACHEL
If you go outside much earlier, Mercury will not have risen high enough for you to see.
PAUL
And if you go outside a little after 6:00 AM, the sun will begin brightening the sky too much to see Mercury clearly.
RACHEL
The very thin waxing crescent moon is located five degrees away from Venus on the evening of the 9th.
PAUL
Look low in the west, as the moon is only three days old.
RACHEL
This ought to be an attractive site in your binoculars.
PAUL
That’s Idaho Skies for the first week of August. Next week is one of the year’s best meteor showers.
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.
Thursday, August 1, 2013
In Greek myth, Ophiuchus is Asclepius the healer. He was born to a mortal mother and his father was the Greek god Apollo. In his youth, Asclepius was given to Chiron the centaur to raise. It was Chiron who trained his adopted son to be healer. Asclepius became such a great healer that he brought several of his dead patients back to life. To prevent him from going too far, Zeus hurled a thunderbolt and killed Asclepius. His father Apollo complained about the death of his son, so Zeus made Asclepius immortal and placed him in the sky as Ophiuchus.
Rasalhague (also called Alpha Ophiuchi and 55 Ophiuchi) is Arabic for "the Head of the Serpent Collector." The star is 47 light years away. Therefore, the light you see from Rasalhague tonight left in 1966. Rasalhague is a double star, but its companion is so close that even a telescope can’t resolve them as separate stars. Rasalhague is spectral type A5 (white in color) and has a surface temperature of 18,000 degrees (compare to 5,800 degrees for the sun). That makes Rasalhague twice as hot and 25 times brighter than our sun. Rasalhague recently (in stellar years) stopped converting hydrogen into helium. Its higher core temperature is permitting the star to generate energy by fusing the helium ash in its core into carbon and oxygen.
Sunday, June 9, 2013
Transcript for June 16 - 22
RACHEL
Welcome to Idaho Skies for the third week of June. We’re your hosts, Rachel…
PAUL
…and Paul.
RACHEL
The moon is first quarter on the 16th.
PAUL
That means it’s time to dust off your old pair of binoculars and take a gander at the moon.
RACHEL
Craters are noticeable in your binoculars, especially in the southern half of the moon.
PAUL
Your best lunar views come from bracing your arms on something sturdy, like a tree or fence.
RACHEL
That way the shaking in your arms will not blur the view.
PAUL
On the 18th, the moon sits between the star Spica and the planet Saturn.
RACHEL
Spica is closer to the moon while Saturn is farther away.
PAUL
You’ll be able to see either the moon and Spica together in binoculars or the moon and Saturn together, but not all three simultaneously.
RACHEL
When you observe Saturn, you’ll see that the star Kappa Virginis in the constellation Virgo is close to Saturn’s upper right.
PAUL
But they’re not close in space. Saturn is 76 light minutes away while Kappa Virginis is 224 light years away.
RACHEL
So the light you see from Saturn only left an hour and fifteen minutes ago while the light of Kappa Virginis left in the year 1789.
PAUL
Thirty years ago on the 18th, the United States launched the first American woman into Earth orbit aboard the Space Shuttle.
RACHEL
Sally Ride was 32 years old when she traveled to space and she still remains the youngest American to travel into space.
PAUL
Sally spent a total of two weeks in space during her two Space Shuttle flights. Both of her flights were on board the Space Shuttle Challenger.
RACHEL
Sally was not the first woman in space, however. She was preceded into space by Soviet cosmonauts Valentina Tereshkova in 1963 and Svetlana Savitskaya in 1982.
PAUL
This week Venus is rising higher above the horizon and Mercury is approaching the horizon.
RACHEL
So the two inner planets cross paths once again on the evening of June 20th.
PAUL
Mercury will be to the lower left of brighter Venus.
RACHEL
They’ll be close enough together that both will be visible together in your binoculars.
PAUL
Begin looking for the pair of planets by 10:00 PM, after the sun has set.
RACHEL
While you’re searching for Venus and Mercury, you may notice there are two stars above and to the right of Venus.
PAUL
These are the brightest two stars of Gemini, Pollux and Castor.
RACHEL
Summer in the northern hemisphere begins late on the evening of the 20th.
PAUL
That means on the 20th, daylight lasts it’s longest for the year.
RACHEL
In Boise, our first day of summer will be 15 hours and 23 minutes long.
PAUL
That’s Idaho Skies for the third week of June. Next week we’ll discuss the full moon, its proximity to Earth, and what effect this will have on us.
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.
Welcome to Idaho Skies for the third week of June. We’re your hosts, Rachel…
PAUL
…and Paul.
RACHEL
The moon is first quarter on the 16th.
PAUL
That means it’s time to dust off your old pair of binoculars and take a gander at the moon.
RACHEL
Craters are noticeable in your binoculars, especially in the southern half of the moon.
PAUL
Your best lunar views come from bracing your arms on something sturdy, like a tree or fence.
RACHEL
That way the shaking in your arms will not blur the view.
PAUL
On the 18th, the moon sits between the star Spica and the planet Saturn.
RACHEL
Spica is closer to the moon while Saturn is farther away.
PAUL
You’ll be able to see either the moon and Spica together in binoculars or the moon and Saturn together, but not all three simultaneously.
RACHEL
When you observe Saturn, you’ll see that the star Kappa Virginis in the constellation Virgo is close to Saturn’s upper right.
PAUL
But they’re not close in space. Saturn is 76 light minutes away while Kappa Virginis is 224 light years away.
RACHEL
So the light you see from Saturn only left an hour and fifteen minutes ago while the light of Kappa Virginis left in the year 1789.
PAUL
Thirty years ago on the 18th, the United States launched the first American woman into Earth orbit aboard the Space Shuttle.
RACHEL
Sally Ride was 32 years old when she traveled to space and she still remains the youngest American to travel into space.
PAUL
Sally spent a total of two weeks in space during her two Space Shuttle flights. Both of her flights were on board the Space Shuttle Challenger.
RACHEL
Sally was not the first woman in space, however. She was preceded into space by Soviet cosmonauts Valentina Tereshkova in 1963 and Svetlana Savitskaya in 1982.
PAUL
This week Venus is rising higher above the horizon and Mercury is approaching the horizon.
RACHEL
So the two inner planets cross paths once again on the evening of June 20th.
PAUL
Mercury will be to the lower left of brighter Venus.
RACHEL
They’ll be close enough together that both will be visible together in your binoculars.
PAUL
Begin looking for the pair of planets by 10:00 PM, after the sun has set.
RACHEL
While you’re searching for Venus and Mercury, you may notice there are two stars above and to the right of Venus.
PAUL
These are the brightest two stars of Gemini, Pollux and Castor.
RACHEL
Summer in the northern hemisphere begins late on the evening of the 20th.
PAUL
That means on the 20th, daylight lasts it’s longest for the year.
RACHEL
In Boise, our first day of summer will be 15 hours and 23 minutes long.
PAUL
That’s Idaho Skies for the third week of June. Next week we’ll discuss the full moon, its proximity to Earth, and what effect this will have on us.
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.
Transcript for June 9 - 15
PAUL
Welcome to Idaho Skies for the second week of June. We’re your hosts, Paul…
RACHEL
…and Rachel.
PAUL
On the evening of the 10th, the young crescent moon passes very close to Mercury and Venus.
RACHEL
You’ll need to look for this trio of astronomical objects after 10:00 PM, but before 10:30. You’ll need a clear west-northwestern horizon to see them, as they will be low.
PAUL
The 10th also marks the tenth anniversary of the launch of the Spirit Mars Rover.
RACHEL
Spirit was one of two solar-powered rovers launched to the red planet in 2003.
PAUL
For six years, Spirit traversed the Martian surface looking for evidence of water in Mars’ past.
RACHEL
The rover traveled nearly five miles during its search and made multiple measurements of the Martian rocks near the Columbia Hills.
PAUL
Spirit’s instruments detected slight chemical alterations in the composition of the outer layers of rocks.
RACHEL
It also found a type of chemical called sulfates in the Martian soil.
PAUL
These results indicated that water was present in the Martian past.
RACHEL
However, the amount was small compared to the amount of water found on Earth.
PAUL
Spirit’s mission ended after it became stuck in soft Martian sand.
RACHEL
Unable to extract itself from the loose sand, Spirit couldn’t properly orient its solar array for the approaching winter.
PAUL
The limited amount of sunlight available during the winter prevented Spirit’s solar array from acquiring enough power to survive the brutal cold.
RACHEL
On June 12th, Mercury is at its greatest eastern elongation.
PAUL
Elongation is a property of the orbits of inner planets and not outer planets.
RACHEL
Inner planets, which astronomers call inferior planets are those that orbit closer to the sun than Earth.
PAUL
Like Mercury and Venus.
RACHEL
And superior planets are those that orbit the sun farther than Earth.
PAUL
Since inferior planets reside closer to the sun than Earth, we will never see them in the sky opposite of the sun.
RACHEL
The greatest distance away from the sun that we see an inferior planet is called its greatest elongation.
PAUL
Because of its small orbit, Mercury can only travel 24 degrees away from the sun.
RACHEL
That sounds impressive. After all, 24 degrees is nearly 1/3rd of the distance from the horizon to overhead.
PAUL
That would be correct if Boise was located on the equator. However, at a latitude of 43 degrees north, Mercury’s orbit around the sun is very slanted with respect to our local horizon.
RACHEL
So how far above the horizon will Mercury appear when its 24 degrees from the sun?
PAUL
Our solar system’s smallest planet will only appear ten degrees above horizon at 10:00 PM. That means by 10:45, the planet will be all but impossible to see.
RACHEL
Hey, the earliest sunrise this year occurs on the 13th!
PAUL
That means from now until mid December, the sun will set earlier each night.
RACHEL
That’s Idaho Skies for the second week of June. Next week the moon passes close to Saturn, so you will have more than just Mercury and Venus to observe.
PAUL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com. For Idaho Skies this is Paul…
RACHEL
and Rachel.
PAUL
Dark skies and bright stars.
Welcome to Idaho Skies for the second week of June. We’re your hosts, Paul…
RACHEL
…and Rachel.
PAUL
On the evening of the 10th, the young crescent moon passes very close to Mercury and Venus.
RACHEL
You’ll need to look for this trio of astronomical objects after 10:00 PM, but before 10:30. You’ll need a clear west-northwestern horizon to see them, as they will be low.
PAUL
The 10th also marks the tenth anniversary of the launch of the Spirit Mars Rover.
RACHEL
Spirit was one of two solar-powered rovers launched to the red planet in 2003.
PAUL
For six years, Spirit traversed the Martian surface looking for evidence of water in Mars’ past.
RACHEL
The rover traveled nearly five miles during its search and made multiple measurements of the Martian rocks near the Columbia Hills.
PAUL
Spirit’s instruments detected slight chemical alterations in the composition of the outer layers of rocks.
RACHEL
It also found a type of chemical called sulfates in the Martian soil.
PAUL
These results indicated that water was present in the Martian past.
RACHEL
However, the amount was small compared to the amount of water found on Earth.
PAUL
Spirit’s mission ended after it became stuck in soft Martian sand.
RACHEL
Unable to extract itself from the loose sand, Spirit couldn’t properly orient its solar array for the approaching winter.
PAUL
The limited amount of sunlight available during the winter prevented Spirit’s solar array from acquiring enough power to survive the brutal cold.
RACHEL
On June 12th, Mercury is at its greatest eastern elongation.
PAUL
Elongation is a property of the orbits of inner planets and not outer planets.
RACHEL
Inner planets, which astronomers call inferior planets are those that orbit closer to the sun than Earth.
PAUL
Like Mercury and Venus.
RACHEL
And superior planets are those that orbit the sun farther than Earth.
PAUL
Since inferior planets reside closer to the sun than Earth, we will never see them in the sky opposite of the sun.
RACHEL
The greatest distance away from the sun that we see an inferior planet is called its greatest elongation.
PAUL
Because of its small orbit, Mercury can only travel 24 degrees away from the sun.
RACHEL
That sounds impressive. After all, 24 degrees is nearly 1/3rd of the distance from the horizon to overhead.
PAUL
That would be correct if Boise was located on the equator. However, at a latitude of 43 degrees north, Mercury’s orbit around the sun is very slanted with respect to our local horizon.
RACHEL
So how far above the horizon will Mercury appear when its 24 degrees from the sun?
PAUL
Our solar system’s smallest planet will only appear ten degrees above horizon at 10:00 PM. That means by 10:45, the planet will be all but impossible to see.
RACHEL
Hey, the earliest sunrise this year occurs on the 13th!
PAUL
That means from now until mid December, the sun will set earlier each night.
RACHEL
That’s Idaho Skies for the second week of June. Next week the moon passes close to Saturn, so you will have more than just Mercury and Venus to observe.
PAUL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com. For Idaho Skies this is Paul…
RACHEL
and Rachel.
PAUL
Dark skies and bright stars.
The light of Arcturus opened the 1933 World’s Fair in Chicago. At that time, the best measurement of the distance to this star pegged it at 40 light years. Since the previous World’s Fair in Chicago occurred forty years earlier, the starlight seen from Arcturus at the opening of the 1933 fair had left the star during the last fair. To open the 1933 World’s Fair, a large telescope lens focused the Arcturian starlight on a photocell (a light-sensitive resistor). The electrical signal generated by the star’s light shining on the photocell was used to switch on the lights of the fair.
Arcturus is a spectral type K star, meaning its cooler than our sun and produces less light per square foot of surface. Instead of being yellow like our sun (which is a G spectral type), Arcturus is a cooler orange. However, because of its larger diameter, Arcturus shines over 100 times more brightly than our sun. If its infrared radiation is included, then the star is over 200 times brighter than our sun. It would take 26 of our suns to span the diameter of Arcturus. If the star replaced the sun in our sky, it would cover an area of the sky two times larger than the palm of your outstretched hand. The surface of Arcturus would reach one-quarter of the way to the orbit of Mercury. Of course, the larger mass, diameter, and radiation from Arcturus would end all life on Earth with the possible exception of bacteria living far underground.
To find Arcturus, follow the bend of the handle of the Big Dipper. An arc drawn from the end of the Dipper’s handle (actually the Large Bear’s tail) leads you to Arcturus. In June, Arcturus passes almost directly overhead.
Monday, June 3, 2013
Transcript for June 2 - 8
RACHEL
Welcome to Idaho Skies for the first week of June. We’re your hosts, Rachel…
PAUL
… and Paul.
RACHEL
Now is the time to observe Mercury, Venus, and Jupiter.
PAUL
Our solar system’s two innermost planets remain close to Jupiter and all three are visible in the western evening sky.
RACHEL
Since Jupiter and Venus are so bright, they make it easier to locate Mercury.
PAUL
To see them, look low in the west-northwestern horizon about 30 minutes after sunset on the 1st.
RACHEL
That evening, Jupiter, Venus, and Mercury will form a straight line that is inclined towards the upper-left.
PAUL
Jupiter will be the lowest and very near the horizon. Venus is brighter and is located to Jupiter’s upper left.
RACHEL
To locate Mercury, just draw a straight line upwards from Jupiter to Venus. Mercury is located the same distance above Venus.
PAUL
Venus continues climbing higher above the horizon this summer.
RACHEL
Jupiter, on the other hand, is passing behind the sun soon and will reappear in the morning sky in another month.
PAUL
What about Mercury? What is its motion in June?
RACHEL
Mercury will climb a bit higher above the horizon until June 10th. Then it will begin approaching the sun, from Earth’s perspective.
PAUL
On the 4th, Venus is just above a cluster of stars named M-35.
RACHEL
It will be difficult to see very well because the sun will have recently set and it will still be dawn.
PAUL
You’ll need to search for this star cluster just below Venus after 10 PM.
RACHEL
However, you won’t have long, Venus sets at 10:30.
PAUL
Speaking of dawn, did you know that there are three types of twilight?
RACHEL
That’s right. The first is called civil twilight. Civil twilight ends when the center of the sun is 6 degrees below the horizon.
PAUL
At the end of civil twilight, we can only see the brightest stars. However, it is dark enough that state laws require us to turn on our car headlights.
RACHEL
The second is nautical twilight. This ends when the center of the sun is 12 degrees below the horizon.
PAUL
At the end of nautical twilight, sailors cannot navigate using observations that require them to see the horizon; the horizon is too dark to distinguish from the sky.
RACHEL
The last is astronomical twilight. At the end of astronomical twilight, the center of the sun is 18 degrees below the horizon.
PAUL
At the end of astronomical twilight, the sky is as dark as it will get. We can see the faintest stars.
RACHEL
The moon is new on the 8th, so you won’t see it for a day or two at best.
PAUL
However, it’s a good time to see faint objects through your telescope or binoculars.
RACHEL
That’s Idaho Skies for the first week of June. Join us next week to hear more about the innermost planets of our solar system.
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.
Welcome to Idaho Skies for the first week of June. We’re your hosts, Rachel…
PAUL
… and Paul.
RACHEL
Now is the time to observe Mercury, Venus, and Jupiter.
PAUL
Our solar system’s two innermost planets remain close to Jupiter and all three are visible in the western evening sky.
RACHEL
Since Jupiter and Venus are so bright, they make it easier to locate Mercury.
PAUL
To see them, look low in the west-northwestern horizon about 30 minutes after sunset on the 1st.
RACHEL
That evening, Jupiter, Venus, and Mercury will form a straight line that is inclined towards the upper-left.
PAUL
Jupiter will be the lowest and very near the horizon. Venus is brighter and is located to Jupiter’s upper left.
RACHEL
To locate Mercury, just draw a straight line upwards from Jupiter to Venus. Mercury is located the same distance above Venus.
PAUL
Venus continues climbing higher above the horizon this summer.
RACHEL
Jupiter, on the other hand, is passing behind the sun soon and will reappear in the morning sky in another month.
PAUL
What about Mercury? What is its motion in June?
RACHEL
Mercury will climb a bit higher above the horizon until June 10th. Then it will begin approaching the sun, from Earth’s perspective.
PAUL
On the 4th, Venus is just above a cluster of stars named M-35.
RACHEL
It will be difficult to see very well because the sun will have recently set and it will still be dawn.
PAUL
You’ll need to search for this star cluster just below Venus after 10 PM.
RACHEL
However, you won’t have long, Venus sets at 10:30.
PAUL
Speaking of dawn, did you know that there are three types of twilight?
RACHEL
That’s right. The first is called civil twilight. Civil twilight ends when the center of the sun is 6 degrees below the horizon.
PAUL
At the end of civil twilight, we can only see the brightest stars. However, it is dark enough that state laws require us to turn on our car headlights.
RACHEL
The second is nautical twilight. This ends when the center of the sun is 12 degrees below the horizon.
PAUL
At the end of nautical twilight, sailors cannot navigate using observations that require them to see the horizon; the horizon is too dark to distinguish from the sky.
RACHEL
The last is astronomical twilight. At the end of astronomical twilight, the center of the sun is 18 degrees below the horizon.
PAUL
At the end of astronomical twilight, the sky is as dark as it will get. We can see the faintest stars.
RACHEL
The moon is new on the 8th, so you won’t see it for a day or two at best.
PAUL
However, it’s a good time to see faint objects through your telescope or binoculars.
RACHEL
That’s Idaho Skies for the first week of June. Join us next week to hear more about the innermost planets of our solar system.
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.
Subscribe to:
Posts (Atom)