RACHEL
Welcome to Idaho Skies for the first week of May. We’re your hosts, Rachel…
PAUL
… and Paul.
RACHEL
The moon is at third quarter on the 2nd.
PAUL
First and third quarter moons are half moons.
RACHEL
The first quarter is the half moon most people see after sunset in the south.
PAUL
Sunlight illuminates the right half of the moon, or the moon’s eastern hemisphere.
RACHEL
At the third quarter moon, the sun illuminates the moon’s western hemisphere. Unlike the first quarter moon, the third quarter moon doesn’t rise until around midnight.
PAUL
The first and third quarter moons are excellent astronomical objects for binoculars and small telescopes.
RACHEL
That’s because the terminator of the first and third quarter moons point directly towards Earth.
PAUL
As a result, the shadows on the face of the moon are stretched their longest from our perspective.
RACHEL
One thing you will notice about the third quarter moon is that the western hemisphere of the moon is covered in more extensive maria than the eastern hemisphere.
PAUL
The maria are vast lava flows that filled ancient impact basins.
RACHEL
This occurred around 3.9 billion years ago when the moon’s interior was still hot.
PAUL
The flooding occurred in waves so each eruption left a thin layer of lava covering the previous eruption.
RACHEL
When you look at the lunar maria though your binoculars, you’ll see layers of rock older than any rocks on Earth.
PAUL
The moon’s largest impact basin is 1,500 miles across and eight miles deep in places. That’s large enough to span one quarter of the moon.
RACHEL
The impact basin is located between the crater Aitken and the moon’s South Pole.
PAUL
Astronomers named this impact basin the South Pole-Aitken basin and it’s the moon’s oldest recognized impact basin.
RACHEL
Because the impact basin is located at the Moon’s South Pole, we were unaware of its existence until spacecraft began exploring the moon in the early 1960s.
PAUL
It wasn’t until the 1990s that scientists mapped the complete topography of the South Pole-Aitken basin, and discovered that it is one of the solar system’s largest impact basins.
RACHEL
May 3rd is Space Day.
PAUL
Space Day is a celebration of humanity’s exploration of outer space. It is sponsored by the aerospace company Lockheed Martin.
RACHEL
Check out the Space Day website to see if anything is happening near you. www.spaceday.org
PAUL
That’s Idaho Skies for the first week of May. Join us next week to hear about Idaho’s next meteor shower.
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.
Saturday, April 27, 2013
Mizar and Alcor
This month look for the stars, Mizar and Alcor. Mizar is the star that forms the bend in the handle of the Big Dipper. Look carefully at this star and you’ll probably notice that it has a fainter companion star very close to it. The name of the companion star is Alcor and it is located at an angle directed away from the direction handle bend. Use a pair of binoculars if you’re not certain that you can see the fainter Alcor. To me, the distance between the two stars is close to the angle that 1/8th of an inch spans when viewed at arm’s distance. It may be hard to believe, but that gives Mizar and Alcor an angular separation close to ½ the diameter of the moon. When you look at Mizar with even slight optical aid, get ready for another surprise; Mizar is a double star. In 1650, Mizar was the first double star that astronomers discovered.
Mizar is over twice as massive as our sun and Alcor is over 50% heavier than our sun. The pair is located between 78 and 81 light years from the earth (the distance is uncertain). Therefore, if you were born between 1935 and 1932, Mizar and Alcor are your birthday stars this year. The actual distance between Mizar and Alcor may be anywhere between ¼ to over three light years. Therefore, it’s possible that these two stars are not actually in orbit around each other. However, if they are in orbit around each other, then their orbital period may be in the hundreds of thousands of years.
What we call The Big Dipper is not a true constellation; it is a part of the constellation of Ursa Major or the Big Bear. The constellation of the Big Bear passes high over the north during May evenings. This means that during April evenings, the Dipper is upside down and pouring its contents on the Earth below.
Sunday, April 21, 2013
Transcript of the Fourth Week of April
RACHEL
Welcome to Idaho Skies for the last week of April. We’re your hosts, Rachel…
PAUL
…and Paul.
RACHEL
Spica, the brightest star in Virgo, is two degrees above the moon on the evening of the 24th.
PAUL
For a sense of perspective, two degrees is approximately the width of your thumb when you fully extend your arm.
RACHEL
Spica will appear so close to the moon that you can see both together in your binoculars.
PAUL
Speaking of the moon, the moon is full on the 25th.
RACHEL
The full moon in April is often called the Egg Moon.
PAUL
When the moon is full, you’ll notice that the moon’s light renders the fainter stars invisible. In hazy or humid air, the full moon can turn the night sky a shade of light blue.
RACHEL
Although the full moon appears bright, it only reflects 12% of the sunlight shining on it.
PAUL
Astronomers use the term albedeo to describe the reflectivity of astronomical objects.
RACHEL
Albedo is a number between 0 and 1. An albedo of zero is not reflective at all and an albedo of 1 is 100% reflective.
PAUL
The moon’s albedo is about 0.12 or equal to the albedo of old asphalt.
RACHEL
Earth’s albedo on the other hand is 0.37, which means our planet reflects 37% of the sunlight shining on it.
PAUL
Can you locate Saturn in the night sky?
RACHEL
Saturn is right above the full moon on the 25th.
PAUL
Saturn will appear as a pale yellow-white star.
RACHEL
Unlike most stars however, Saturn will not twinkle.
PAUL
You need a telescope in order to see the planet’s rings; binoculars are not powerful enough.
RACHEL
Saturn and the moon rise by nine PM. So wait until at least 9:30 to look for Saturn.
PAUL
Three nights later Saturn reaches opposition.
RACHEL
That means on the 28th, Saturn is located directly opposite the sun in our sky.
PAUL
This also means that Saturn is closest to Earth.
RACHEL
At a distance of 860 million miles, the light you see from Saturn spent an hour and 17 minutes traversing the vacuum of outer space to reach your eye.
PAUL
A car driving at 70 miles per hour would need 1,400 years to reach Saturn at opposition.
RACHEL
That’s Idaho Skies for the last week of April. Listen next month for the astronomical events occurring 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.
Welcome to Idaho Skies for the last week of April. We’re your hosts, Rachel…
PAUL
…and Paul.
RACHEL
Spica, the brightest star in Virgo, is two degrees above the moon on the evening of the 24th.
PAUL
For a sense of perspective, two degrees is approximately the width of your thumb when you fully extend your arm.
RACHEL
Spica will appear so close to the moon that you can see both together in your binoculars.
PAUL
Speaking of the moon, the moon is full on the 25th.
RACHEL
The full moon in April is often called the Egg Moon.
PAUL
When the moon is full, you’ll notice that the moon’s light renders the fainter stars invisible. In hazy or humid air, the full moon can turn the night sky a shade of light blue.
RACHEL
Although the full moon appears bright, it only reflects 12% of the sunlight shining on it.
PAUL
Astronomers use the term albedeo to describe the reflectivity of astronomical objects.
RACHEL
Albedo is a number between 0 and 1. An albedo of zero is not reflective at all and an albedo of 1 is 100% reflective.
PAUL
The moon’s albedo is about 0.12 or equal to the albedo of old asphalt.
RACHEL
Earth’s albedo on the other hand is 0.37, which means our planet reflects 37% of the sunlight shining on it.
PAUL
Can you locate Saturn in the night sky?
RACHEL
Saturn is right above the full moon on the 25th.
PAUL
Saturn will appear as a pale yellow-white star.
RACHEL
Unlike most stars however, Saturn will not twinkle.
PAUL
You need a telescope in order to see the planet’s rings; binoculars are not powerful enough.
RACHEL
Saturn and the moon rise by nine PM. So wait until at least 9:30 to look for Saturn.
PAUL
Three nights later Saturn reaches opposition.
RACHEL
That means on the 28th, Saturn is located directly opposite the sun in our sky.
PAUL
This also means that Saturn is closest to Earth.
RACHEL
At a distance of 860 million miles, the light you see from Saturn spent an hour and 17 minutes traversing the vacuum of outer space to reach your eye.
PAUL
A car driving at 70 miles per hour would need 1,400 years to reach Saturn at opposition.
RACHEL
That’s Idaho Skies for the last week of April. Listen next month for the astronomical events occurring 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, April 14, 2013
Transcript for the Third Week of April
PAUL
Welcome to Idaho Skies for the third week of April. We’re your hosts, Paul…
RACHEL
…and Rachel.
PAUL
The moon is at first quarter on the 18th.
RACHEL
That’s the moon’s prefect phase. The shadows cast by the sun rising above the moon’s terminator make craters and mountains more visible.
PAUL
In your binoculars, you may notice there is a mountain range in the upper-right quadrant of the moon.
RACHEL
That’s the Caucasus Mountains, named after the mountain range located between the Black Sea and the Caspian Sea.
PAUL
On the moon, they surround the western edge of the Sea of Serenity and are 19,000 feet high in places.
RACHEL
That means some of the lunar peaks that you can see in your binoculars are 50% taller than Mount Borah.
PAUL
April 20th is Astronomy Day.
RACHEL
Astronomy Day is the day that astronomy enthusiasts bring astronomy to the general public.
PAUL
At the Discovery Center of Idaho, the Boise Astronomical Society will set up a telescope for solar viewing.
RACHEL
The telescope will have a filter to make it safe to look at sunspots.
PAUL
The Herrett Center is also planning activities
RACHEL
The museum opens early at 10 AM and visitors can take part in several make and take activities, like water bottle rockets.
PAUL
You can watch four shows at the Faulkner planetarium.
RACHEL
Later that evening, there will be a star party at the Herrett center. Visitors will be able to look through a variety of telescopes and see the moon and Saturn.
PAUL
The events at DCI and the Herrett Center are weather dependent. If the sky is cloudy, the telescope events will be cancelled.
RACHEL
The Lyrid meteor shower peaks on the night of the 21st and 22nd.
PAUL
Meteoroids are the remains of comet tails. They travel in orbits that closely follow their parent comet.
RACHEL
The comet’s orbit becomes filled with meteoric dust, called a meteor stream.
PAUL
When the meteor stream crosses Earth’s orbit, there is potential for a meteor shower.
RACHEL
In truth, many potential meteor showers never create meteors. That’s because Earth is located in the wrong place in its orbit when the meteor stream crosses its orbit.
PAUL
When the Earth and the meteor stream intersect, we observe meteors. The meteors appear to radiate from one point in the sky.
RACHEL
That point is called the meteor’s radiant and is usually named after the constellation in which it occurs.
PAUL
The radiant of the Lyrids appears beneath the bright star Vega in the constellation of Lyra.
RACHEL
The radiant of the Lyrid meteor shower rises by 8:00 PM. However, the moon is a waxing gibbous that night.
PAUL
Since the moon won’t set until after 4:00 AM, your best view of the meteor shower won’t occur until very early on the morning of the 22nd.
RACHEL
You might see as many as ten swift meteors per hour from this shower.
PAUL
That’s Idaho Skies for the third week of April. Next week we’ll tell you about albedo, or the reflectivity of the planets. We’ll also tell you where you can find Saturn.
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…
RACHEL
and Rachel.
PAUL
Dark skies and bright stars.
Welcome to Idaho Skies for the third week of April. We’re your hosts, Paul…
RACHEL
…and Rachel.
PAUL
The moon is at first quarter on the 18th.
RACHEL
That’s the moon’s prefect phase. The shadows cast by the sun rising above the moon’s terminator make craters and mountains more visible.
PAUL
In your binoculars, you may notice there is a mountain range in the upper-right quadrant of the moon.
RACHEL
That’s the Caucasus Mountains, named after the mountain range located between the Black Sea and the Caspian Sea.
PAUL
On the moon, they surround the western edge of the Sea of Serenity and are 19,000 feet high in places.
RACHEL
That means some of the lunar peaks that you can see in your binoculars are 50% taller than Mount Borah.
PAUL
April 20th is Astronomy Day.
RACHEL
Astronomy Day is the day that astronomy enthusiasts bring astronomy to the general public.
PAUL
At the Discovery Center of Idaho, the Boise Astronomical Society will set up a telescope for solar viewing.
RACHEL
The telescope will have a filter to make it safe to look at sunspots.
PAUL
The Herrett Center is also planning activities
RACHEL
The museum opens early at 10 AM and visitors can take part in several make and take activities, like water bottle rockets.
PAUL
You can watch four shows at the Faulkner planetarium.
RACHEL
Later that evening, there will be a star party at the Herrett center. Visitors will be able to look through a variety of telescopes and see the moon and Saturn.
PAUL
The events at DCI and the Herrett Center are weather dependent. If the sky is cloudy, the telescope events will be cancelled.
RACHEL
The Lyrid meteor shower peaks on the night of the 21st and 22nd.
PAUL
Meteoroids are the remains of comet tails. They travel in orbits that closely follow their parent comet.
RACHEL
The comet’s orbit becomes filled with meteoric dust, called a meteor stream.
PAUL
When the meteor stream crosses Earth’s orbit, there is potential for a meteor shower.
RACHEL
In truth, many potential meteor showers never create meteors. That’s because Earth is located in the wrong place in its orbit when the meteor stream crosses its orbit.
PAUL
When the Earth and the meteor stream intersect, we observe meteors. The meteors appear to radiate from one point in the sky.
RACHEL
That point is called the meteor’s radiant and is usually named after the constellation in which it occurs.
PAUL
The radiant of the Lyrids appears beneath the bright star Vega in the constellation of Lyra.
RACHEL
The radiant of the Lyrid meteor shower rises by 8:00 PM. However, the moon is a waxing gibbous that night.
PAUL
Since the moon won’t set until after 4:00 AM, your best view of the meteor shower won’t occur until very early on the morning of the 22nd.
RACHEL
You might see as many as ten swift meteors per hour from this shower.
PAUL
That’s Idaho Skies for the third week of April. Next week we’ll tell you about albedo, or the reflectivity of the planets. We’ll also tell you where you can find Saturn.
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…
RACHEL
and Rachel.
PAUL
Dark skies and bright stars.
Monday, April 8, 2013
Transcript for April 8 to 14
RACHEL
Welcome to Idaho Skies for the second week of April. We’re your hosts, Rachel…
PAUL
…and Paul.
RACHEL
The moon is new on the 10th.
PAUL
If you’re searching for faint galaxies through your telescope, you’ll want to look for them before and after the night of the 10th.
RACHEL
That’s because the moonlight drowns out many of the fainter objects in the sky.
PAUL
What do astronomers call the brightness of an astronomical object?
RACHEL
They call the brightness of an object its magnitude. The Greek astronomer Hipparchus originally developed the stellar magnitude system in the second century BC.
PAUL
We best remember Hipparchus for his catalog of stars. It was the first major catalog of stars. His catalog contained entries for the brightness and position of 850 stars.
RACHEL
Hipparchus gave the brightest stars a magnitude of one. The magnitudes of fainter stars were given larger numbers.
PAUL
So does this mean that a star of magnitude two is fainter than a magnitude one star but brighter than a magnitude three star?
RACHEL
That’s right. Hipparchus’ faintest stars were given a magnitude of six.
PAUL
Because of the way our senses operate, a first magnitude star does not emit twice the amount of light of a second magnitude star.
RACHEL
A star appearing one magnitude brighter is actually two and a half times brighter.
PAUL
A first magnitude star is therefore one hundred times brighter than a sixth magnitude star.
RACHEL
If the brightest stars are given a magnitude of one, then what is the magnitude of the sun and moon?
PAUL
They are given negative magnitudes. So, the full moon is -12.5 magnitude and the sun is -26.5 magnitude.
RACHEL
The perfect magnitude zero star is Vega and it passes over Boise at 5:30 AM in April.
PAUL
On April 12, 1961, Yuri Gagarin became the first person to orbit Earth.
RACHEL
In recognition of this historic event, April 12th is called Yuri's Night.
PAUL
Visitors to the Discovery Center of Idaho can make stomp rockets in celebration of Yuri’s orbit of Earth on April 12th.
RACHEL
The Teen Club will have a rocketry display.
PAUL
The moon is your guide to Jupiter on the evening of the 14th.
RACHEL
Jupiter will appear as a bright star just west of the four-day old moon.
PAUL
The crescent moon and Jupiter are close enough together to observe them at the same time in your binoculars.
RACHEL
Once you find Jupiter, steady your binoculars on a tree or car.
PAUL
You’ll find there are three faint stars forming a line with Jupiter.
RACHEL
These are three of Jupiter’s four large satellites. In a small telescope, all four satellites are visible.
PAUL
The satellite appearing most distant from Jupiter and therefore easiest to see is Callisto.
RACHEL
Next in line and closer to Jupiter is Ganymede, the largest satellite in the solar system.
PAUL
Closer still to Jupiter is Europa, a satellite with a deep liquid ocean covered in a crust of ice.
RACHEL
Check the Idaho Skies blog for a map of Jupiter and its satellites on the night of the 14th.
PAUL
That’s Idaho Skies for the second week of April. Next week is our first meteor shower in three months. It’s also Astronomy Day and there are a lot of activities for the public to enjoy.
RACHEL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com. For Idaho Skies this is Rachel…
PAUL
and Paul.
RACHEL
Dark skies and bright stars.
Welcome to Idaho Skies for the second week of April. We’re your hosts, Rachel…
PAUL
…and Paul.
RACHEL
The moon is new on the 10th.
PAUL
If you’re searching for faint galaxies through your telescope, you’ll want to look for them before and after the night of the 10th.
RACHEL
That’s because the moonlight drowns out many of the fainter objects in the sky.
PAUL
What do astronomers call the brightness of an astronomical object?
RACHEL
They call the brightness of an object its magnitude. The Greek astronomer Hipparchus originally developed the stellar magnitude system in the second century BC.
PAUL
We best remember Hipparchus for his catalog of stars. It was the first major catalog of stars. His catalog contained entries for the brightness and position of 850 stars.
RACHEL
Hipparchus gave the brightest stars a magnitude of one. The magnitudes of fainter stars were given larger numbers.
PAUL
So does this mean that a star of magnitude two is fainter than a magnitude one star but brighter than a magnitude three star?
RACHEL
That’s right. Hipparchus’ faintest stars were given a magnitude of six.
PAUL
Because of the way our senses operate, a first magnitude star does not emit twice the amount of light of a second magnitude star.
RACHEL
A star appearing one magnitude brighter is actually two and a half times brighter.
PAUL
A first magnitude star is therefore one hundred times brighter than a sixth magnitude star.
RACHEL
If the brightest stars are given a magnitude of one, then what is the magnitude of the sun and moon?
PAUL
They are given negative magnitudes. So, the full moon is -12.5 magnitude and the sun is -26.5 magnitude.
RACHEL
The perfect magnitude zero star is Vega and it passes over Boise at 5:30 AM in April.
PAUL
On April 12, 1961, Yuri Gagarin became the first person to orbit Earth.
RACHEL
In recognition of this historic event, April 12th is called Yuri's Night.
PAUL
Visitors to the Discovery Center of Idaho can make stomp rockets in celebration of Yuri’s orbit of Earth on April 12th.
RACHEL
The Teen Club will have a rocketry display.
PAUL
The moon is your guide to Jupiter on the evening of the 14th.
RACHEL
Jupiter will appear as a bright star just west of the four-day old moon.
PAUL
The crescent moon and Jupiter are close enough together to observe them at the same time in your binoculars.
RACHEL
Once you find Jupiter, steady your binoculars on a tree or car.
PAUL
You’ll find there are three faint stars forming a line with Jupiter.
RACHEL
These are three of Jupiter’s four large satellites. In a small telescope, all four satellites are visible.
PAUL
The satellite appearing most distant from Jupiter and therefore easiest to see is Callisto.
RACHEL
Next in line and closer to Jupiter is Ganymede, the largest satellite in the solar system.
PAUL
Closer still to Jupiter is Europa, a satellite with a deep liquid ocean covered in a crust of ice.
RACHEL
Check the Idaho Skies blog for a map of Jupiter and its satellites on the night of the 14th.
PAUL
That’s Idaho Skies for the second week of April. Next week is our first meteor shower in three months. It’s also Astronomy Day and there are a lot of activities for the public to enjoy.
RACHEL
Be sure to read our blog for additional information. It’s at idahoskies dot blogspot dot com. For Idaho Skies this is Rachel…
PAUL
and Paul.
RACHEL
Dark skies and bright stars.
Tuesday, April 2, 2013
Transcript for April 3 - 9
PAUL
Welcome to Idaho Skies for the first week of April. We’re your hosts, Paul…
RACHEL
… and Rachel.
PAUL
The moon is at last quarter on the 2nd.
RACHEL
That means the moon appears as a half moon. In this case, it will be the left half or the western side of the moon that is illuminated.
PAUL
Most people haven’t observed the last quarter moon. So if you have the chance, spend a few minutes with the moon on the morning of the 2nd.
RACHEL
Through your binoculars, you’ll notice that several large dark maria cover the last quarter moon. Some of the maria are marked with bright craters.
PAUL
The brightest craters are Copernicus, Kepler, and Aristarchus.
RACHEL
Copernicus, Kepler, and Aristarchus were astronomers who advocated for the sun-centered view of the universe.
PAUL
Father Riccioli, a church astronomer, named these craters and the lunar seas surrounding them.
RACHEL
He was not a fan of the heliocentric theory, so the names of the lunar seas imply less than ideal weather.
PAUL
The craters of Copernicus, Kepler, and Aristarchus are located in the Ocean of Storms and the Sea of Rains.
RACHEL
Did you know that it wasn’t until the 1960s that astronomers and geologists finally settled on an explanation for the formation of craters?
PAUL
Many astronomers and geologists initially thought that volcanic activity was the cause of moon craters.
RACHEL
Instrumental in our modern understanding of crater formation was the work of geologist Eugene Shoemaker.
PAUL
By studying Meteor Crater in Arizona, Shoemaker convinced other geologists that craters are formed by meteor impacts.
RACHEL
April 5th is the 40th anniversary of the launch of Pioneer 11.
PAUL
This spacecraft is a 569 pound robotic explorer of the outer solar system. It was originally designed as a flyby mission of Jupiter.
RACHEL
However, after a successful encounter of Jupiter by its predecessor, Pioneer 10, Pioneer 11 flew past Jupiter and was then redirected to Saturn.
PAUL
During its flyby of Saturn in 1979, the spacecraft narrowly avoided a collision with the moon Epimetheus, an unknown satellite at the time.
RACHEL
Pioneer 11 was the first spacecraft to fly past Saturn. It was a trailblazer for Voyager 1, which would fly past Saturn a year later.
PAUL
NASA was uncertain about the safety of flying Voyager near the rings of Saturn, so they used Pioneer 11 to test the trajectory.
RACHEL
Today this dead spacecraft is 8 billion miles from the sun. That’s nearly three times farther away than the orbit of Pluto.
PAUL
That’s Idaho Skies for the first week of April. Next week we’ll explain how a Greek astronomer over 2,000 years ago developed the system we use to classify the brightness of stars.
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 April. We’re your hosts, Paul…
RACHEL
… and Rachel.
PAUL
The moon is at last quarter on the 2nd.
RACHEL
That means the moon appears as a half moon. In this case, it will be the left half or the western side of the moon that is illuminated.
PAUL
Most people haven’t observed the last quarter moon. So if you have the chance, spend a few minutes with the moon on the morning of the 2nd.
RACHEL
Through your binoculars, you’ll notice that several large dark maria cover the last quarter moon. Some of the maria are marked with bright craters.
PAUL
The brightest craters are Copernicus, Kepler, and Aristarchus.
RACHEL
Copernicus, Kepler, and Aristarchus were astronomers who advocated for the sun-centered view of the universe.
PAUL
Father Riccioli, a church astronomer, named these craters and the lunar seas surrounding them.
RACHEL
He was not a fan of the heliocentric theory, so the names of the lunar seas imply less than ideal weather.
PAUL
The craters of Copernicus, Kepler, and Aristarchus are located in the Ocean of Storms and the Sea of Rains.
RACHEL
Did you know that it wasn’t until the 1960s that astronomers and geologists finally settled on an explanation for the formation of craters?
PAUL
Many astronomers and geologists initially thought that volcanic activity was the cause of moon craters.
RACHEL
Instrumental in our modern understanding of crater formation was the work of geologist Eugene Shoemaker.
PAUL
By studying Meteor Crater in Arizona, Shoemaker convinced other geologists that craters are formed by meteor impacts.
RACHEL
April 5th is the 40th anniversary of the launch of Pioneer 11.
PAUL
This spacecraft is a 569 pound robotic explorer of the outer solar system. It was originally designed as a flyby mission of Jupiter.
RACHEL
However, after a successful encounter of Jupiter by its predecessor, Pioneer 10, Pioneer 11 flew past Jupiter and was then redirected to Saturn.
PAUL
During its flyby of Saturn in 1979, the spacecraft narrowly avoided a collision with the moon Epimetheus, an unknown satellite at the time.
RACHEL
Pioneer 11 was the first spacecraft to fly past Saturn. It was a trailblazer for Voyager 1, which would fly past Saturn a year later.
PAUL
NASA was uncertain about the safety of flying Voyager near the rings of Saturn, so they used Pioneer 11 to test the trajectory.
RACHEL
Today this dead spacecraft is 8 billion miles from the sun. That’s nearly three times farther away than the orbit of Pluto.
PAUL
That’s Idaho Skies for the first week of April. Next week we’ll explain how a Greek astronomer over 2,000 years ago developed the system we use to classify the brightness of stars.
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.
Regulus
Regulus is larger than our sun and has a mass 3-1/2 times greater. Its extra mass causes the star to consume its supply of hydrogen at a faster rate than the sun. As a result, Regulus shines 240 times brighter than our sun. If viewed from Regulus, our sun would be so dim that we could not see it without the aid of a telescope. However, Regulus is easily seen in town. Regulus has a faint companion star that orbits it in a 130,000 year long orbit. This faint star is actually two stars in orbit around each other. It only takes this pair 1,000 years to complete one orbit around each other.
The constellation of Leo passes overhead at 9:00 PM in early April and 8:00 PM in late April. When you see Leo, you will probably first notice its backwards question mark of stars. The question mark, or sickle of Leo, consists of six stars and opens towards the west. The question mark represents the head and neck of Leo, with Leo’s head looking to the west. The bottom star of this question mark is Regulus. East of the sickle of Leo are his hind quarters and it is represented by three stars forming a triangle pointing east. The moon is a convenient guide to Leo on the 21st when it will be directly beneath the constellation.
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