RACHEL
Welcome to Idaho Skies for the fifth week of May. We’re your hosts, Rachel…
PAUL
…and Paul.
RACHEL
The moon is last quarter on the 29th.
PAUL
Which means it’s also a nice to observe the moon through your binoculars.
RACHEL
More importantly, the moon has a neighbor that night and it’s a bit of an astronomical challenge to see.
PAUL
The challenge is our eighth planet, Neptune.
RACHEL
This icy giant planet is just 4.5 degrees away from the moon on the 29th.
PAUL
That means you can see both together in a pair of binoculars because binoculars typically have a field of view of 5 degrees.
RACHEL
You’ll need dark skies in order to see Neptune, so leave town for the countryside.
PAUL
Once in a dark location, place the moon on the right edge of your binoculars.
RACHEL
Then find the brightest star directly east of the moon and the far edge of your binoculars.
PAUL
A small distance farther east of the bright star is a faint star that will be as bright as Neptune.
RACHEL
And the distance between the star and the brighter star is the same distance Neptune is away from the bright star.
PAUL
Now Neptune is the other faint star down and slightly left of the bright star.
RACHEL
The bright star, its neighboring faint star, and Neptune will form a small triangle with a 90 degree apex centered on the bright star.
PAUL
It will be better to place the moon outside your view when you search for Neptune.
RACHEL
You’ll find a star map for you to use on both Idaho Skies on Twitter and Blog Spot.
PAUL
If you get a chance to see Neptune, remember that you’re looking at the most distant planet in the solar system.
RACHEL
The average distance between Earth and Neptune is 2.7 billion miles.
PAUL
At a diameter of 30,600 miles, Neptune is almost four times the size of Earth.
RACHEL
Its mass is 17 times greater than Earth.
PAUL
Why only 17 times more massive? Shouldn’t be more like four times four times four or 64 times more massive?
RACHEL
The reason for the discrepancy is that while Earth is rocky, Neptune is mostly water and gas.
PAUL
The moon is close to the eastern horizon as you drive to work on the 31st.
RACHEL
Can you see Earthshine on the moon?
PAUL
Binoculars will definitely help.
RACHEL
But please don’t use your binoculars while you drive.
PAUL
It’s Saturn’s turn to reach opposition on June 3rd.
RACHEL
This means Earth is passing Saturn as the planets orbit around the sun.
PAUL
The reason Earth can pass the superior planets is because Earth’s orbit around the sun is smaller.
RACHEL
Smaller orbits are closer to the sun and therefore under the influence of a stronger gravitational field.
PAUL
Stronger gravitational fields mean orbital speeds must be higher to maintain a constant distance from the sun.
RACHEL
So if Earth wasn’t traveling faster, then it would spiral into the sun.
PAUL
Barbeque anyone?
RACHEL
That’s Idaho Skies for the last week of May. Next week is another opportunity to see Earthshine.
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.
Tuesday, May 31, 2016
Monday, May 23, 2016
Transcript for May 22nd to 28th
PAUL
Welcome to Idaho Skies for the fourth week of May. We’re your hosts, Paul…
RACHEL
…and Rachel.
PAUL
Mars reaches opposition on the 22nd.
RACHEL
At opposition, superior planets…
PAUL
…or those beyond Earth…
RACHEL
…are at their closest to Earth for the year.
PAUL
Opposition occurs when the faster orbital motion of Earth results in it catching up to and passing the superior planet in question.
RACHEL
In the process of reaching opposition, superior planets appear to retrograde, or move slightly backwards across the stars.
PAUL
Retrograde motion is an illusion however.
RACHEL
It’s caused by the changing perspective between Earth and superior planets when compared to the fixed stars.
PAUL
Hundreds of years ago…
RACHEL
…that’s when the geocentric or Earth-centered solar system was in vogue…
PAUL
…astronomers and philosophers believed the superior planets actually moved backwards during a short period of time at retrograde.
RACHEL
This was possible because astronomers believed these planets orbited Earth in a set of nested orbits of various sizes.
PAUL
In the 16th century, Copernicus convinced astronomers otherwise.
RACHEL
He explained that retrograde motion was easier to understand when you move the sun to the center of the solar system and demoted Earth to a planet orbiting the sun.
PAUL
In time, other astronomers accepted this explanation, especially after the work of Johannes Kepler in the 17th century.
RACHEL
The bright yellowish star visible to the right of the moon on the 22nd is Saturn.
PAUL
You’ll need at a spotting scope or telescope capable of magnifying at least 25 times in order to see the planet’s rings.
RACHEL
And its largest satellite, Titan.
PAUL
Titan is a fascinating world.
RACHEL
Yes it is. It’s larger than Earth’s moon and cloaked in an atmosphere denser than Earth’s.
PAUL
Unfortunately, it’s also intensely cold on Titan.
RACHEL
How cold?
PAUL
So cold that methane, a gas used to heat our homes, is a liquid.
RACHEL
So cold that its nitrogen-rich atmosphere is almost cold enough to liquefy.
PAUL
Because of its dense atmosphere, Titan has weather.
RACHEL
However, its dense atmosphere prevents it weather from being as dynamic as Earth’s weather
PAUL
Still, this still allows it to rain on Titan.
RACHEL
On Titan, it’s a methane rain falling on rock hard pebbles of water ice.
PAUL
In 2005, the Huygens probe landed on Titan and returned images for 90 minutes.
RACHEL
Those images showed a landscape not too unlike Earth.
PAUL
Including mountains eroded by falling methane rain
RACHEL
And a stream bed where once a liquid methane stream once flowed.
PAUL
That’s Idaho Skies for the fourth week of May. We have a challenge for you next week, to see Neptune in your binoculars.
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.
Welcome to Idaho Skies for the fourth week of May. We’re your hosts, Paul…
RACHEL
…and Rachel.
PAUL
Mars reaches opposition on the 22nd.
RACHEL
At opposition, superior planets…
PAUL
…or those beyond Earth…
RACHEL
…are at their closest to Earth for the year.
PAUL
Opposition occurs when the faster orbital motion of Earth results in it catching up to and passing the superior planet in question.
RACHEL
In the process of reaching opposition, superior planets appear to retrograde, or move slightly backwards across the stars.
PAUL
Retrograde motion is an illusion however.
RACHEL
It’s caused by the changing perspective between Earth and superior planets when compared to the fixed stars.
PAUL
Hundreds of years ago…
RACHEL
…that’s when the geocentric or Earth-centered solar system was in vogue…
PAUL
…astronomers and philosophers believed the superior planets actually moved backwards during a short period of time at retrograde.
RACHEL
This was possible because astronomers believed these planets orbited Earth in a set of nested orbits of various sizes.
PAUL
In the 16th century, Copernicus convinced astronomers otherwise.
RACHEL
He explained that retrograde motion was easier to understand when you move the sun to the center of the solar system and demoted Earth to a planet orbiting the sun.
PAUL
In time, other astronomers accepted this explanation, especially after the work of Johannes Kepler in the 17th century.
RACHEL
The bright yellowish star visible to the right of the moon on the 22nd is Saturn.
PAUL
You’ll need at a spotting scope or telescope capable of magnifying at least 25 times in order to see the planet’s rings.
RACHEL
And its largest satellite, Titan.
PAUL
Titan is a fascinating world.
RACHEL
Yes it is. It’s larger than Earth’s moon and cloaked in an atmosphere denser than Earth’s.
PAUL
Unfortunately, it’s also intensely cold on Titan.
RACHEL
How cold?
PAUL
So cold that methane, a gas used to heat our homes, is a liquid.
RACHEL
So cold that its nitrogen-rich atmosphere is almost cold enough to liquefy.
PAUL
Because of its dense atmosphere, Titan has weather.
RACHEL
However, its dense atmosphere prevents it weather from being as dynamic as Earth’s weather
PAUL
Still, this still allows it to rain on Titan.
RACHEL
On Titan, it’s a methane rain falling on rock hard pebbles of water ice.
PAUL
In 2005, the Huygens probe landed on Titan and returned images for 90 minutes.
RACHEL
Those images showed a landscape not too unlike Earth.
PAUL
Including mountains eroded by falling methane rain
RACHEL
And a stream bed where once a liquid methane stream once flowed.
PAUL
That’s Idaho Skies for the fourth week of May. We have a challenge for you next week, to see Neptune in your binoculars.
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, May 16, 2016
Transcript for May 15th to 21st
RACHEL
Welcome to Idaho Skies for the third week of May. We’re your hosts, Rachel…
PAUL
…and Paul.
RACHEL
The moon passes very close to Spica on the night of the 17th.
PAUL
Spica is the brightest star of Virgo the Maiden, which is the second largest constellation in the sky.
RACHEL
Only the constellation of Hydra is larger.
PAUL
Hydra is the constellation of the water snake and its located east of Virgo.
RACHEL
Virgo is made up of dim stars, so the constellation doesn’t stand out to the extent that its large size would indicate.
PAUL
One depiction of Virgo is as a goddess of justice named Justitia.
RACHEL
In this guise, she holds the scales of justice in her hands.
PAUL
And those scales are represented by the constellation of Libra the Scales.
RACHEL
So it’s not surprising that a widely spaced double star located in Libra can be found below the moon two days later on the 19th.
PAUL
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.
RACHEL
The rest of us need a pair of binoculars.
PAUL
You’ll find the double star 5 degrees below the moon on the night of the 19th.
RACHEL
So to find it, place the moon at the top of your binocular’s view.
PAUL
Then Zubenelgenubi will appear as the bright pair of stars at the bottom of your view.
RACHEL
The moon is full on the 21st.
PAUL
The full moon in May is called the Flower Moon by some people.
RACHEL
This year the Flower moon located between the planets Mars and Saturn.
PAUL
Mars is the bright orange-tinted star to the right of the moon.
RACHEL
And Saturn is the fainter yellow-white star to the lower left of the moon.
PAUL
Currently, there are five spacecraft orbiting Mars, three American, one European, and one Indian.
RACHEL
On Mars are two functioning rovers.
PAUL
They’re named Opportunity and Curiosity
RACHEL
Unfortunately, there’s only one spacecraft orbiting Saturn, Cassini.
PAUL
Below the moon is another orange star, Antares.
RACHEL
Antares is a red giant star and it represents the heart of Scorpius the Scorpion.
PAUL
Antares has the same color as Mars, but it’s not quite as bright as Mars these days.
RACHEL
That’s because Earth is approaching close to Mars.
PAUL
As Earth and Mars approach one another, Mars changes from an average orangish star into a bright orange beacon.
RACHEL
So when you observe Mars and Antares these days, look for their similar color but distinctly different brightness.
PAUL
That’s Idaho Skies for the third week of May. Mars reaches opposition next week and we’ll tell more about it.
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 May. We’re your hosts, Rachel…
PAUL
…and Paul.
RACHEL
The moon passes very close to Spica on the night of the 17th.
PAUL
Spica is the brightest star of Virgo the Maiden, which is the second largest constellation in the sky.
RACHEL
Only the constellation of Hydra is larger.
PAUL
Hydra is the constellation of the water snake and its located east of Virgo.
RACHEL
Virgo is made up of dim stars, so the constellation doesn’t stand out to the extent that its large size would indicate.
PAUL
One depiction of Virgo is as a goddess of justice named Justitia.
RACHEL
In this guise, she holds the scales of justice in her hands.
PAUL
And those scales are represented by the constellation of Libra the Scales.
RACHEL
So it’s not surprising that a widely spaced double star located in Libra can be found below the moon two days later on the 19th.
PAUL
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.
RACHEL
The rest of us need a pair of binoculars.
PAUL
You’ll find the double star 5 degrees below the moon on the night of the 19th.
RACHEL
So to find it, place the moon at the top of your binocular’s view.
PAUL
Then Zubenelgenubi will appear as the bright pair of stars at the bottom of your view.
RACHEL
The moon is full on the 21st.
PAUL
The full moon in May is called the Flower Moon by some people.
RACHEL
This year the Flower moon located between the planets Mars and Saturn.
PAUL
Mars is the bright orange-tinted star to the right of the moon.
RACHEL
And Saturn is the fainter yellow-white star to the lower left of the moon.
PAUL
Currently, there are five spacecraft orbiting Mars, three American, one European, and one Indian.
RACHEL
On Mars are two functioning rovers.
PAUL
They’re named Opportunity and Curiosity
RACHEL
Unfortunately, there’s only one spacecraft orbiting Saturn, Cassini.
PAUL
Below the moon is another orange star, Antares.
RACHEL
Antares is a red giant star and it represents the heart of Scorpius the Scorpion.
PAUL
Antares has the same color as Mars, but it’s not quite as bright as Mars these days.
RACHEL
That’s because Earth is approaching close to Mars.
PAUL
As Earth and Mars approach one another, Mars changes from an average orangish star into a bright orange beacon.
RACHEL
So when you observe Mars and Antares these days, look for their similar color but distinctly different brightness.
PAUL
That’s Idaho Skies for the third week of May. Mars reaches opposition next week and we’ll tell more about it.
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, May 9, 2016
Transcript: May 8th to 14th
PAUL
Welcome to Idaho Skies for the second week of May. We’re your hosts, Paul…
RACHEL
…and Rachel.
PAUL
The moon reappears in the low west-northwest on the 8th.
RACHEL
It’s been absent from the sky for the last four days because it’s been too close to the sun.
PAUL
So after it gets dark after 10:00 PM on the 8th, look for the moon and see if you can detect Earthshine illuminating its dark portion.
RACHEL
Earthshine will be most visible if you view the moon through binoculars.
PAUL
You can make additional observations of Earthshine for several more nights.
RACHEL
Mercury made an evening appearance last month.
PAUL
However, it disappeared before the end of April.
RACHEL
This month Mercury passes between Earth and the sun and Idahoans get to see a part of that passage.
PAUL
This event is called a transit and it only happens on an average of 13 times per century.
RACHEL
The transit begins on the 9th at around 7:00 AM in Idaho and ends shortly after noon.
PAUL
Now a transit is not safe to observe directly with your eyes, since it requires looking at the sun.
RACHEL
This means that a telescope properly covered with solar viewing filters can directly observe the transit of Mercury, but other instruments cannot.
PAUL
Check the website for the Boise Astronomical Society for times and locations that you can see the transit.
RACHEL
Or try using the projection method of observing the sun.
PAUL
How can you project an image of the sun?
RACHEL
If you can aim a pair of binoculars, spotting scope, or small telescope at the sun, then you can project an image.
PAUL
Do NOT look at this image through the eyepiece.
RACHEL
Instead, place a sheet of white paper several inches to an foot away from the eyepiece of your scope or binoculars.
PAUL
Then focus the scope or binoculars until the image of the sun is sharp.
RACHEL
Any sunspots visible during the transit will appear irregularly shaped with fuzzy edges.
PAUL
While Mercury will appear as a tiny round dot with sharp edges.
RACHEL
Mercury will travel across the sun south of its equator from Earth’s perspective.
PAUL
But remember that if you observe the transit with a telescope, the image will be upside down.
RACHEL
Hey, want to see a really nice star cluster on the night of the 11th?
PAUL
The star cluster’s named is the Beehive Star Cluster and you’ll find it 7 degrees above the moon.
RACHEL
To see this attractive star cluster, point you binoculars at the moon and then tilt them directly north of the moon.
PAUL
Just after the moon leaves the binoculars’ view, the Beehive will appear at the top of the field of view.
RACHEL
You should see a striking similarity between the Beehive star cluster and a swarm of bees.
PAUL
What’s that bright star above the moon on the night of the 14th?
RACHEL
Why it’s Jupiter, the King of the solar system’s planets.
PAUL
Both are so close that you can see them both together in your binoculars.
RACHEL
You’ll notice that Jupiter is accompanied by a retinue of satellites.
PAUL
From left to right, the moons will be Callisto, Europa, Jupiter, and Ganymede.
RACHEL
There’s an even closer moon that you can see if you use a small telescope.
PAUL
It’s Jupiter’s innermost moon Io and it appears near the right edge of Jupiter in a telescope.
RACHEL
That’s Idaho Skies for the second week of May. Next week the Flower Moon passes between two bright planets.
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.
Welcome to Idaho Skies for the second week of May. We’re your hosts, Paul…
RACHEL
…and Rachel.
PAUL
The moon reappears in the low west-northwest on the 8th.
RACHEL
It’s been absent from the sky for the last four days because it’s been too close to the sun.
PAUL
So after it gets dark after 10:00 PM on the 8th, look for the moon and see if you can detect Earthshine illuminating its dark portion.
RACHEL
Earthshine will be most visible if you view the moon through binoculars.
PAUL
You can make additional observations of Earthshine for several more nights.
RACHEL
Mercury made an evening appearance last month.
PAUL
However, it disappeared before the end of April.
RACHEL
This month Mercury passes between Earth and the sun and Idahoans get to see a part of that passage.
PAUL
This event is called a transit and it only happens on an average of 13 times per century.
RACHEL
The transit begins on the 9th at around 7:00 AM in Idaho and ends shortly after noon.
PAUL
Now a transit is not safe to observe directly with your eyes, since it requires looking at the sun.
RACHEL
This means that a telescope properly covered with solar viewing filters can directly observe the transit of Mercury, but other instruments cannot.
PAUL
Check the website for the Boise Astronomical Society for times and locations that you can see the transit.
RACHEL
Or try using the projection method of observing the sun.
PAUL
How can you project an image of the sun?
RACHEL
If you can aim a pair of binoculars, spotting scope, or small telescope at the sun, then you can project an image.
PAUL
Do NOT look at this image through the eyepiece.
RACHEL
Instead, place a sheet of white paper several inches to an foot away from the eyepiece of your scope or binoculars.
PAUL
Then focus the scope or binoculars until the image of the sun is sharp.
RACHEL
Any sunspots visible during the transit will appear irregularly shaped with fuzzy edges.
PAUL
While Mercury will appear as a tiny round dot with sharp edges.
RACHEL
Mercury will travel across the sun south of its equator from Earth’s perspective.
PAUL
But remember that if you observe the transit with a telescope, the image will be upside down.
RACHEL
Hey, want to see a really nice star cluster on the night of the 11th?
PAUL
The star cluster’s named is the Beehive Star Cluster and you’ll find it 7 degrees above the moon.
RACHEL
To see this attractive star cluster, point you binoculars at the moon and then tilt them directly north of the moon.
PAUL
Just after the moon leaves the binoculars’ view, the Beehive will appear at the top of the field of view.
RACHEL
You should see a striking similarity between the Beehive star cluster and a swarm of bees.
PAUL
What’s that bright star above the moon on the night of the 14th?
RACHEL
Why it’s Jupiter, the King of the solar system’s planets.
PAUL
Both are so close that you can see them both together in your binoculars.
RACHEL
You’ll notice that Jupiter is accompanied by a retinue of satellites.
PAUL
From left to right, the moons will be Callisto, Europa, Jupiter, and Ganymede.
RACHEL
There’s an even closer moon that you can see if you use a small telescope.
PAUL
It’s Jupiter’s innermost moon Io and it appears near the right edge of Jupiter in a telescope.
RACHEL
That’s Idaho Skies for the second week of May. Next week the Flower Moon passes between two bright planets.
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.
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.
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
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!
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