Last quarter moon is September 2-3

The moon was almost exactly at last quarter when Deirdre Horan in Dublin, Ireland, captured this photo. The terminator line, or line between light and dark on the moon, appears straight.

When the moon appears half-lit in sunshine and half-immersed in the moon’s own shadow – when it rises in the middle of the night – astronomers say it is at last quarter. Before sunrise on April 8, 2018, the moon was at or near its last quarter phase. A last quarter moon always rises in the middle of the night, appears at its highest in the sky around dawn, and sets around midday.

On a last quarter moon, the lunar terminator – the shadow line dividing day and night – shows you where it’s sunset on the moon.

A last quarter moon provides a great opportunity to think of yourself on a three-dimensional world in space. For example, it’s fun to see this moon just after moonrise, shortly after midnight. Then the lighted portion points downward, to the sun below your feet. Think of the last quarter moon as a mirror to the world you’re standing on. Think of yourself standing in the middle of Earth’s nightside, on the midnight portion of Earth.

Also, a last quarter moon can be used as a guidepost to Earth’s direction of motion in orbit around the sun.

In other words, when you look toward a last quarter moon high in the predawn sky, for example, you’re gazing out approximately along the path of Earth’s orbit, in a forward direction. The moon is moving in orbit around the sun with the Earth and never holds still. But, if we could somehow anchor the moon in space … tie it down, keep it still … Earth’s orbital speed of 18 miles per second would carry us across the space between us and the moon in only a few hours.

A great thing about this observation is that it can be done from anywhere, for example, as in the photo below, from large cities.

Ben Orlove wrote from New York City: “I was sitting in the roof garden of my building, and there was the moon, right in front of me. You were right, this is a perfect time to visualize … the Earth’s motion.”

As the moon orbits Earth, it changes phase in an orderly way. Follow the link below to understand the phases of the moon.

New moon
Waxing crescent moon
First quarter moon
Waxing gibbous moon
Full moon
Waning gibbous moon
Last quarter moon
Waning crescent moon

Read more: 4 keys to understanding moon phases

Bottom line: The next last quarter moon is September 3, 2018, at 02:37 UTC; translate UTC to your time.



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The moon was almost exactly at last quarter when Deirdre Horan in Dublin, Ireland, captured this photo. The terminator line, or line between light and dark on the moon, appears straight.

When the moon appears half-lit in sunshine and half-immersed in the moon’s own shadow – when it rises in the middle of the night – astronomers say it is at last quarter. Before sunrise on April 8, 2018, the moon was at or near its last quarter phase. A last quarter moon always rises in the middle of the night, appears at its highest in the sky around dawn, and sets around midday.

On a last quarter moon, the lunar terminator – the shadow line dividing day and night – shows you where it’s sunset on the moon.

A last quarter moon provides a great opportunity to think of yourself on a three-dimensional world in space. For example, it’s fun to see this moon just after moonrise, shortly after midnight. Then the lighted portion points downward, to the sun below your feet. Think of the last quarter moon as a mirror to the world you’re standing on. Think of yourself standing in the middle of Earth’s nightside, on the midnight portion of Earth.

Also, a last quarter moon can be used as a guidepost to Earth’s direction of motion in orbit around the sun.

In other words, when you look toward a last quarter moon high in the predawn sky, for example, you’re gazing out approximately along the path of Earth’s orbit, in a forward direction. The moon is moving in orbit around the sun with the Earth and never holds still. But, if we could somehow anchor the moon in space … tie it down, keep it still … Earth’s orbital speed of 18 miles per second would carry us across the space between us and the moon in only a few hours.

A great thing about this observation is that it can be done from anywhere, for example, as in the photo below, from large cities.

Ben Orlove wrote from New York City: “I was sitting in the roof garden of my building, and there was the moon, right in front of me. You were right, this is a perfect time to visualize … the Earth’s motion.”

As the moon orbits Earth, it changes phase in an orderly way. Follow the link below to understand the phases of the moon.

New moon
Waxing crescent moon
First quarter moon
Waxing gibbous moon
Full moon
Waning gibbous moon
Last quarter moon
Waning crescent moon

Read more: 4 keys to understanding moon phases

Bottom line: The next last quarter moon is September 3, 2018, at 02:37 UTC; translate UTC to your time.



from EarthSky https://ift.tt/1m8DkdY

All 8 planets in 1 night, from Rome

View larger. | As the night of August 28, 2018, began, Gianluca Masi of the Virtual Telescope Project caught the first planets – Venus and Jupiter – shining above the Great Synagogue of Rome, at sunset. Earth in the foreground qualifies as a planet, too.

This was was published originally at the Virtual Telescope Project and appears here with permission.

I have been thinking for decades about seeing and hopefully imagining all eight planets of our solar system in one night, from sunset to dawn. And I did it on the night of August 28-29, 2018, in a very special way: I imaged all of them from Rome, above the amazing monuments of the Eternal City. It was hard, but it was fun!

Spying the entire planetary family in one night is not straightforward. You need all the planets to be far enough from the sun, away from its intense light, but this happens from time to time. In 2016, I succeeded in observing and imaging the five bright planets – Mercury, Venus, Mars, Jupiter and Saturn – at a glance, when they offered a great view . Again, earlier this month, I could capture four of the five bright planets crossing the starry catwalk above Rome.

Of course, the Earth in the foreground qualified as a planet, too.

Since Pluto got demoted from being considered a planet in 2006, the remaining planets, the two faint ones – Uranus and Neptune – can be seen even with a very modest binocular. These two planets – which move slowly around the sun, and so slowly in front of the star background – have been for some years among the stars of Northern Hemisphere autumn, a season we are approaching. Uranus and Neptune are now up in the middle of the night.

Thus the official, current eight planets of our solar system are available for a wonderful grand tour, if you carefully choose the right moment, weather included.

And these days are just perfect!

View larger. | Poster of the Gianluca Masi’s 8 planets in 1 night – August 28-29, 2018 – via Virtual Telescope Project.

With Venus leaving the evening sky pretty soon, I had to wait for Mercury to show at dawn. It is there now. I was ready to go, but in a special manner: instead of observing them in a plain way, I wanted to image them from Rome (not an easy location for Uranus and Neptune, being faint enough and difficult to see under severe light pollution), framing each with a monument of the Eternal City.

Such a solar system imaging marathon was never done with this idea in mind, to my knowledge.

I prepared my imaging gear, consisting of two Canon 5DmIV DSLR bodies and two lenses: a Canon EF 24-70mm f/2.8L II USM and a Canon EF 70-200mm f/2.8L IS II USM. Of course, I had a sturdy tripod to put all this on it.

As Uranus and especially Neptune are faint to see from a big city, I had to carefully select the imaging location and the monuments to include in their pictures. I studied this in depth, also considering my long-time experience in imaging the sky from the city, selecting some very suitable places, both for the imaging conditions and the presence of an illustrious monument. With everything set and ready to go, I decided to go out on the night of August 28-29, beginning this cosmic tour. The moon was also going to show, adding to the planetary family in a nice way.

Venus requires immediate action soon after sunset, as it leaves the sky soon after sunset.

Jupiter is not far from Venus, providing a great sight: two of the brightest celestial objects at a glance. My image of both of them, above the Synagogue of Rome, is at the top of this post. First two planets secured! Easily and safely, I would say.

Then, I changed my location, bringing with me the heavy payload I mentioned above. I understand why people looked at me in such a curious way.

Next stop was the Roman Forum, to grab Saturn and Mars. I managed to include the Temple of Saturn (how appropriate!) and the Temple of Vespasian and Titus in such a capture. Seeing this area at night is always breathtaking and having planets and stars above is mind-blowing. In a few minutes, under a dozen curious eyes, I was ready and started imaging. The image is below; I hope you like it, too.

View larger. | As night deepened on August 28, 2018, Gianluca Masi caught the 4th and 5th planets, Saturn and Mars, above the Temple of Saturn and the Temple of Vespasian and Titus, in the Roman Forum.

Of course, I enjoyed all this with my very own eyes: technology is great, but as humans we need to feed our five senses with beauty. Time to leave for another planet!

The third stop was planned to capture Neptune, the farthest of the eight planets, hence the faintest. For the most difficult object, I wanted a legendary monument and luckily in Rome we have the immortal Colosseum. It was the gem of Rome I wanted in my picture of Neptune, despite that the planet was going to be visible as a mere dot of very faint light. I took 10 images, then I averaged them to increase the quality of the weak signal of Neptune and I must admit it worked very well.

Below you can check and judge yourself.

View larger. | Gianluca Masi caught Planet Neptune above the Colosseum and the Roman Forum on August 28, 2018. Photo via Virtual Telescope Project.

But I knew someone was going to enter the scenery and join the trip …

On the left of the picture above, you can see some glare. That is the moon rising behind the Basilica of Maxentius. Switching to my other camera, with a longer lens and, waiting for a while to have it perfectly placed, the moon joined the tour in a great way.

View larger. | The moon enters the scene on the Basilica of Maxentius, with the Colosseum on the right on August 28, 2018. Photo via Virtual Telescope Project.

Once done with the moon, I had to wait for Uranus to climb the sky, so I took a little rest. It was really needed, I cannot tell you how much I walked. I remembered I had no dinner, so I did a ride to home to get some energy back, later going out again, under the stars.

The location for Uranus was, again, the Roman Forum, where I studied this time a vertical image: I carefully included the small, but wonderful Pleiades open cluster, visible about midway up on the left side of the image as a very small dipper.

Uranus is marked and labelled for your convenience. This time, I averaged three images.

Uranus is discreetly shining above the Roman Forum, with the Pleiades star cluster – a tiny dipper – visible midway up on the left. August 28, 2018. Photo via Virtual Telescope Project.

Then, the only missing planet was Mercury. It was going to rise at dawn, so I decided to go home and have a couple of hours of sleeping. When the clock alarm shouted it was time to move, I quickly left home and drove to the Janiculum Hill, facing east, where I had to wait for Mercury. I was alone there, the temperature was 19 Celsius degrees (66 degrees Fahrenheit) … Summer will not last forever.

I started imaging when Mercury was just a few degrees above the horizon, while the twilight already started and I could see the planet in my images first, then I could see it with the eye alone.

The panorama of Rome from there was honestly superb.

View larger. | Just before the sun rose, Gianluca Masi captured Mercury rising above Rome and its precious monuments, August 29, 2018. Photo via Virtual Telescope Project.

At this point the grand tour was over. I was very tired, but it was hard to leave, after such a journey. I traveled for billions of kilometers, back and forth through our solar system, spotting all its eight planets (Earth included, as the foreground in my images!) and the moon above some of the most precious monuments and symbols of our culture and history.

I hope this long report was able to bring to you my experience and feelings and that your time used to read it was well spent. I can say that living this experience was amazing, one of those things leaving great memories and feeding our love for the Cosmos and Beauty.

My friend Bob King wrote a nice article about seeing the eight planets, by the way. Check it out here!

You have a few days left to do the same journey, go out and try. Good luck!

Bottom line: All eight planets of our solar system, captured in one night, above the ancient monuments of Rome!

Help support the Virtual Telescope Project



from EarthSky https://ift.tt/2LQJBd0

View larger. | As the night of August 28, 2018, began, Gianluca Masi of the Virtual Telescope Project caught the first planets – Venus and Jupiter – shining above the Great Synagogue of Rome, at sunset. Earth in the foreground qualifies as a planet, too.

This was was published originally at the Virtual Telescope Project and appears here with permission.

I have been thinking for decades about seeing and hopefully imagining all eight planets of our solar system in one night, from sunset to dawn. And I did it on the night of August 28-29, 2018, in a very special way: I imaged all of them from Rome, above the amazing monuments of the Eternal City. It was hard, but it was fun!

Spying the entire planetary family in one night is not straightforward. You need all the planets to be far enough from the sun, away from its intense light, but this happens from time to time. In 2016, I succeeded in observing and imaging the five bright planets – Mercury, Venus, Mars, Jupiter and Saturn – at a glance, when they offered a great view . Again, earlier this month, I could capture four of the five bright planets crossing the starry catwalk above Rome.

Of course, the Earth in the foreground qualified as a planet, too.

Since Pluto got demoted from being considered a planet in 2006, the remaining planets, the two faint ones – Uranus and Neptune – can be seen even with a very modest binocular. These two planets – which move slowly around the sun, and so slowly in front of the star background – have been for some years among the stars of Northern Hemisphere autumn, a season we are approaching. Uranus and Neptune are now up in the middle of the night.

Thus the official, current eight planets of our solar system are available for a wonderful grand tour, if you carefully choose the right moment, weather included.

And these days are just perfect!

View larger. | Poster of the Gianluca Masi’s 8 planets in 1 night – August 28-29, 2018 – via Virtual Telescope Project.

With Venus leaving the evening sky pretty soon, I had to wait for Mercury to show at dawn. It is there now. I was ready to go, but in a special manner: instead of observing them in a plain way, I wanted to image them from Rome (not an easy location for Uranus and Neptune, being faint enough and difficult to see under severe light pollution), framing each with a monument of the Eternal City.

Such a solar system imaging marathon was never done with this idea in mind, to my knowledge.

I prepared my imaging gear, consisting of two Canon 5DmIV DSLR bodies and two lenses: a Canon EF 24-70mm f/2.8L II USM and a Canon EF 70-200mm f/2.8L IS II USM. Of course, I had a sturdy tripod to put all this on it.

As Uranus and especially Neptune are faint to see from a big city, I had to carefully select the imaging location and the monuments to include in their pictures. I studied this in depth, also considering my long-time experience in imaging the sky from the city, selecting some very suitable places, both for the imaging conditions and the presence of an illustrious monument. With everything set and ready to go, I decided to go out on the night of August 28-29, beginning this cosmic tour. The moon was also going to show, adding to the planetary family in a nice way.

Venus requires immediate action soon after sunset, as it leaves the sky soon after sunset.

Jupiter is not far from Venus, providing a great sight: two of the brightest celestial objects at a glance. My image of both of them, above the Synagogue of Rome, is at the top of this post. First two planets secured! Easily and safely, I would say.

Then, I changed my location, bringing with me the heavy payload I mentioned above. I understand why people looked at me in such a curious way.

Next stop was the Roman Forum, to grab Saturn and Mars. I managed to include the Temple of Saturn (how appropriate!) and the Temple of Vespasian and Titus in such a capture. Seeing this area at night is always breathtaking and having planets and stars above is mind-blowing. In a few minutes, under a dozen curious eyes, I was ready and started imaging. The image is below; I hope you like it, too.

View larger. | As night deepened on August 28, 2018, Gianluca Masi caught the 4th and 5th planets, Saturn and Mars, above the Temple of Saturn and the Temple of Vespasian and Titus, in the Roman Forum.

Of course, I enjoyed all this with my very own eyes: technology is great, but as humans we need to feed our five senses with beauty. Time to leave for another planet!

The third stop was planned to capture Neptune, the farthest of the eight planets, hence the faintest. For the most difficult object, I wanted a legendary monument and luckily in Rome we have the immortal Colosseum. It was the gem of Rome I wanted in my picture of Neptune, despite that the planet was going to be visible as a mere dot of very faint light. I took 10 images, then I averaged them to increase the quality of the weak signal of Neptune and I must admit it worked very well.

Below you can check and judge yourself.

View larger. | Gianluca Masi caught Planet Neptune above the Colosseum and the Roman Forum on August 28, 2018. Photo via Virtual Telescope Project.

But I knew someone was going to enter the scenery and join the trip …

On the left of the picture above, you can see some glare. That is the moon rising behind the Basilica of Maxentius. Switching to my other camera, with a longer lens and, waiting for a while to have it perfectly placed, the moon joined the tour in a great way.

View larger. | The moon enters the scene on the Basilica of Maxentius, with the Colosseum on the right on August 28, 2018. Photo via Virtual Telescope Project.

Once done with the moon, I had to wait for Uranus to climb the sky, so I took a little rest. It was really needed, I cannot tell you how much I walked. I remembered I had no dinner, so I did a ride to home to get some energy back, later going out again, under the stars.

The location for Uranus was, again, the Roman Forum, where I studied this time a vertical image: I carefully included the small, but wonderful Pleiades open cluster, visible about midway up on the left side of the image as a very small dipper.

Uranus is marked and labelled for your convenience. This time, I averaged three images.

Uranus is discreetly shining above the Roman Forum, with the Pleiades star cluster – a tiny dipper – visible midway up on the left. August 28, 2018. Photo via Virtual Telescope Project.

Then, the only missing planet was Mercury. It was going to rise at dawn, so I decided to go home and have a couple of hours of sleeping. When the clock alarm shouted it was time to move, I quickly left home and drove to the Janiculum Hill, facing east, where I had to wait for Mercury. I was alone there, the temperature was 19 Celsius degrees (66 degrees Fahrenheit) … Summer will not last forever.

I started imaging when Mercury was just a few degrees above the horizon, while the twilight already started and I could see the planet in my images first, then I could see it with the eye alone.

The panorama of Rome from there was honestly superb.

View larger. | Just before the sun rose, Gianluca Masi captured Mercury rising above Rome and its precious monuments, August 29, 2018. Photo via Virtual Telescope Project.

At this point the grand tour was over. I was very tired, but it was hard to leave, after such a journey. I traveled for billions of kilometers, back and forth through our solar system, spotting all its eight planets (Earth included, as the foreground in my images!) and the moon above some of the most precious monuments and symbols of our culture and history.

I hope this long report was able to bring to you my experience and feelings and that your time used to read it was well spent. I can say that living this experience was amazing, one of those things leaving great memories and feeding our love for the Cosmos and Beauty.

My friend Bob King wrote a nice article about seeing the eight planets, by the way. Check it out here!

You have a few days left to do the same journey, go out and try. Good luck!

Bottom line: All eight planets of our solar system, captured in one night, above the ancient monuments of Rome!

Help support the Virtual Telescope Project



from EarthSky https://ift.tt/2LQJBd0

Why you can smell rain

Your nose knows what’s on the way. Image via Lucy Chian/Unsplash.

By Tim Logan, Texas A&M University

When those first fat drops of summer rain fall to the hot, dry ground, have you ever noticed a distinctive odor? I have childhood memories of family members who were farmers describing how they could always “smell rain” right before a storm.

Of course rain itself has no scent. But moments before a rain event, an “earthy” smell known as petrichor does permeate the air. People call it musky, fresh – generally pleasant.

This smell actually comes from the moistening of the ground. Australian scientists first documented the process of petrichor formation in 1964 and scientists from the Massachusetts Institute of Technology further studied the mechanics of the process in the 2010s.

Petrichor’s main ingredients are made by plants and bacteria that live in the ground.. Image via Vovan/Shutterstock.

Petrichor is a combination of fragrant chemical compounds. Some are from oils made by plants. The main contributor to petrichor are actinobacteria. These tiny microorganisms can be found in rural and urban areas as well as in marine environments. They decompose dead or decaying organic matter into simple chemical compounds which can then become nutrients for developing plants and other organisms.

A byproduct of their activity is an organic compound called geosmin which contributes to the petrichor scent. Geosmin is a type of alcohol, like rubbing alcohol. Alcohol molecules tend to have a strong scent, but the complex chemical structure of geosmin makes it especially noticeable to people even at extremely low levels. Our noses can detect just a few parts of geosmin per trillion of air molecules.

During a prolonged period of dryness when it has not rained for several days, the decomposition activity rate of the actinobacteria slows down. Just before a rain event, the air becomes more humid and the ground begins to moisten. This process helps to speed up the activity of the actinobacteria and more geosmin is formed.

Before you see it, do you smell it? Image via Shutterstock.

When raindrops fall on the ground, especially porous surfaces such as loose soil or rough concrete, they will splatter and eject tiny particles called aerosols. The geosmin and other petrichor compounds that may be present on the ground or dissolved within the raindrop are released in aerosol form and carried by the wind to surrounding areas. If the rainfall is heavy enough, the petrichor scent can travel rapidly downwind and alert people that rain is soon on the way.

The scent eventually goes away after the storm has passed and the ground begins to dry. This leaves the actinobacteria lying in wait – ready to help us know when it might rain again.

Tim Logan, Instructional Assistant Professor of Atmospheric Sciences, Texas A&M University

This article was originally published on The Conversation. Read the original article.

Bottom line: What is the smell of rain? It’s called petrichor.

The Conversation



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Your nose knows what’s on the way. Image via Lucy Chian/Unsplash.

By Tim Logan, Texas A&M University

When those first fat drops of summer rain fall to the hot, dry ground, have you ever noticed a distinctive odor? I have childhood memories of family members who were farmers describing how they could always “smell rain” right before a storm.

Of course rain itself has no scent. But moments before a rain event, an “earthy” smell known as petrichor does permeate the air. People call it musky, fresh – generally pleasant.

This smell actually comes from the moistening of the ground. Australian scientists first documented the process of petrichor formation in 1964 and scientists from the Massachusetts Institute of Technology further studied the mechanics of the process in the 2010s.

Petrichor’s main ingredients are made by plants and bacteria that live in the ground.. Image via Vovan/Shutterstock.

Petrichor is a combination of fragrant chemical compounds. Some are from oils made by plants. The main contributor to petrichor are actinobacteria. These tiny microorganisms can be found in rural and urban areas as well as in marine environments. They decompose dead or decaying organic matter into simple chemical compounds which can then become nutrients for developing plants and other organisms.

A byproduct of their activity is an organic compound called geosmin which contributes to the petrichor scent. Geosmin is a type of alcohol, like rubbing alcohol. Alcohol molecules tend to have a strong scent, but the complex chemical structure of geosmin makes it especially noticeable to people even at extremely low levels. Our noses can detect just a few parts of geosmin per trillion of air molecules.

During a prolonged period of dryness when it has not rained for several days, the decomposition activity rate of the actinobacteria slows down. Just before a rain event, the air becomes more humid and the ground begins to moisten. This process helps to speed up the activity of the actinobacteria and more geosmin is formed.

Before you see it, do you smell it? Image via Shutterstock.

When raindrops fall on the ground, especially porous surfaces such as loose soil or rough concrete, they will splatter and eject tiny particles called aerosols. The geosmin and other petrichor compounds that may be present on the ground or dissolved within the raindrop are released in aerosol form and carried by the wind to surrounding areas. If the rainfall is heavy enough, the petrichor scent can travel rapidly downwind and alert people that rain is soon on the way.

The scent eventually goes away after the storm has passed and the ground begins to dry. This leaves the actinobacteria lying in wait – ready to help us know when it might rain again.

Tim Logan, Instructional Assistant Professor of Atmospheric Sciences, Texas A&M University

This article was originally published on The Conversation. Read the original article.

Bottom line: What is the smell of rain? It’s called petrichor.

The Conversation



from EarthSky https://ift.tt/2NbMxFO

Catch Venus, Jupiter, Arcturus at dusk

Throughout September, 2018, find an unobstructed horizon in the direction of sunset and watch for two brilliant planets and one bright star to pop out into the your western sky at dusk. In their order of brilliance, these bright beauties are the planets Venus and Jupiter, plus the star Arcturus. Given clear skies and an unobstructed western horizon, the gorgeous threesome – Venus, Jupiter and Arcturus – should be easy to view from most places worldwide.

The sky charts above and below are designed for around 40 degrees north latitude (United States, Spain, Turkey, Japan). If you live at far-northern latitudes, however, you might not see Venus. That’s because – for example – at 60 degrees north latitude (the latitude of Anchorage, Alaska), the sun and Venus set at about the same time.

From the Southern Hemisphere, you’ll see Jupiter more directly above Venus (rather than to Venus’ upper left). Moreover, Venus and Jupiter stay out considerably longer after sunset in the Southern Hemisphere than they do in the Northern Hemisphere.

If you can’t see the star Spica next to Venus or the star Zubenelgenubi next to Jupiter with the eye alone, try your luck with binoculars.

Arcturus is a different story altogether. From the tropical regions of the globe, Arcturus appears lower down in the sky, more to the right (rather than the upper right) of Venus and Jupiter. In early September 2018, at 20 degrees north latitude (Hawaii and Mexico City), Jupiter and Arcturus set about the same time; and at 20 degrees south latitude, it’s Venus and Arcturus that set at about the same time.

Farther south, in the temperate regions of the the Southern Hemisphere, Arcturus is found to the lower right of Venus. At these southerly latitudes, Arcturus sets before Venus does.

Click here for a recommended sky almanac giving you the settings times for the sun, Venus, Jupiter and Arcturus

Have binoculars? Aim them at Venus and you might spot Spica, the brightest star in the constellation Virgo the Maiden, in the same binocular field together. Then aim binoculars at Jupiter to view Zubenelgenubi, the alpha star of the constellation Libra the Scales, taking stage in the same binocular field with Jupiter. (See sky chart above.)

Bottom line: Look west at dusk throughout September, 2018, for a bright celestial threesome. In order of brightness, they are Venus, Jupiter and the star Arcturus.



from EarthSky https://ift.tt/2wB4C6J

Throughout September, 2018, find an unobstructed horizon in the direction of sunset and watch for two brilliant planets and one bright star to pop out into the your western sky at dusk. In their order of brilliance, these bright beauties are the planets Venus and Jupiter, plus the star Arcturus. Given clear skies and an unobstructed western horizon, the gorgeous threesome – Venus, Jupiter and Arcturus – should be easy to view from most places worldwide.

The sky charts above and below are designed for around 40 degrees north latitude (United States, Spain, Turkey, Japan). If you live at far-northern latitudes, however, you might not see Venus. That’s because – for example – at 60 degrees north latitude (the latitude of Anchorage, Alaska), the sun and Venus set at about the same time.

From the Southern Hemisphere, you’ll see Jupiter more directly above Venus (rather than to Venus’ upper left). Moreover, Venus and Jupiter stay out considerably longer after sunset in the Southern Hemisphere than they do in the Northern Hemisphere.

If you can’t see the star Spica next to Venus or the star Zubenelgenubi next to Jupiter with the eye alone, try your luck with binoculars.

Arcturus is a different story altogether. From the tropical regions of the globe, Arcturus appears lower down in the sky, more to the right (rather than the upper right) of Venus and Jupiter. In early September 2018, at 20 degrees north latitude (Hawaii and Mexico City), Jupiter and Arcturus set about the same time; and at 20 degrees south latitude, it’s Venus and Arcturus that set at about the same time.

Farther south, in the temperate regions of the the Southern Hemisphere, Arcturus is found to the lower right of Venus. At these southerly latitudes, Arcturus sets before Venus does.

Click here for a recommended sky almanac giving you the settings times for the sun, Venus, Jupiter and Arcturus

Have binoculars? Aim them at Venus and you might spot Spica, the brightest star in the constellation Virgo the Maiden, in the same binocular field together. Then aim binoculars at Jupiter to view Zubenelgenubi, the alpha star of the constellation Libra the Scales, taking stage in the same binocular field with Jupiter. (See sky chart above.)

Bottom line: Look west at dusk throughout September, 2018, for a bright celestial threesome. In order of brightness, they are Venus, Jupiter and the star Arcturus.



from EarthSky https://ift.tt/2wB4C6J

2018 SkS Weekly Climate Change & Global Warming News Roundup #35

A chronological listing of news articles posted on the Skeptical Science Facebook Page during the past week.

Editor's Pick

Most land-based ecosystems worldwide risk ‘major transformation’ due to climate change

most-land-based-ecosystems-worldwide-risk-major-transformation-due-to-climate-change-map-

Researchers compiled and evaluated pollen and plant-fossil records from nearly 600 sites worldwide for their study of vegetation change. Map reprinted with permission from Nolan et al., Science, 2018 (10.1126/science.aan5360).

Without dramatic reductions in greenhouse-gas emissions, most of the planet’s land-based ecosystems—from its forests and grasslands to the deserts and tundra—are at high risk of “major transformation” due to climate change, according to a new study from an international research team.

The researchers used fossil records of global vegetation change that occurred during a period of post-glacial warming to project the magnitude of ecosystem transformations likely in the future under various greenhouse gas emissions scenarios.

They found that under a “business as usual” emissions scenario, in which little is done to rein in heat-trapping greenhouse-gas emissions, vegetation changes across the planet’s wild landscapes will likely be more far-reaching and disruptive than earlier studies suggested.

The changes would threaten global biodiversity and derail vital services that nature provides to humanity, such as water security, carbon storage and recreation, according to study co-author Jonathan Overpeck, dean of the School for Environment and Sustainability at the University of Michigan.

“If we allow climate change to go unchecked, the vegetation of this planet is going to look completely different than it does today, and that means a huge risk to the diversity of the planet,” said Overpeck, who conceived the idea for the study with corresponding author Stephen T. Jackson of the U.S. Geological Survey.

Most land-based ecosystems worldwide risk ‘major transformation’ due to climate change, Michigan News (University of Michigan), Aug 30, 2018


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from Skeptical Science https://ift.tt/2wDt9az
A chronological listing of news articles posted on the Skeptical Science Facebook Page during the past week.

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Most land-based ecosystems worldwide risk ‘major transformation’ due to climate change

most-land-based-ecosystems-worldwide-risk-major-transformation-due-to-climate-change-map-

Researchers compiled and evaluated pollen and plant-fossil records from nearly 600 sites worldwide for their study of vegetation change. Map reprinted with permission from Nolan et al., Science, 2018 (10.1126/science.aan5360).

Without dramatic reductions in greenhouse-gas emissions, most of the planet’s land-based ecosystems—from its forests and grasslands to the deserts and tundra—are at high risk of “major transformation” due to climate change, according to a new study from an international research team.

The researchers used fossil records of global vegetation change that occurred during a period of post-glacial warming to project the magnitude of ecosystem transformations likely in the future under various greenhouse gas emissions scenarios.

They found that under a “business as usual” emissions scenario, in which little is done to rein in heat-trapping greenhouse-gas emissions, vegetation changes across the planet’s wild landscapes will likely be more far-reaching and disruptive than earlier studies suggested.

The changes would threaten global biodiversity and derail vital services that nature provides to humanity, such as water security, carbon storage and recreation, according to study co-author Jonathan Overpeck, dean of the School for Environment and Sustainability at the University of Michigan.

“If we allow climate change to go unchecked, the vegetation of this planet is going to look completely different than it does today, and that means a huge risk to the diversity of the planet,” said Overpeck, who conceived the idea for the study with corresponding author Stephen T. Jackson of the U.S. Geological Survey.

Most land-based ecosystems worldwide risk ‘major transformation’ due to climate change, Michigan News (University of Michigan), Aug 30, 2018


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Moonlight over Black Waterfall, Iceland

Svartifoss under moonlight in iceland by Grafixart Sam.

Grafixart Sam submitted this photo of Svartifoss (the Black Waterfall) on August 31, 2018. This glorious waterfall is located in Iceland’s Vatnajökull National Park, on Iceland’s south coast. It drops 65 feet (20 meters) and got its name because the cliff from which it falls is made of hexagonal black basalt columns, of a type found elsewhere in Iceland.

Here’s a great description of hiking to Svartifoss

Thank you, Grafixart Sam!

Svartifoss – the Black Waterfall – takes its name from the black basalt columns in the cliff from which it drops. Photo via GlacierGuides.

Bottom line: Photo of Svartifoss, in Iceland, under moonlight.



from EarthSky https://ift.tt/2C7Ac1n

Svartifoss under moonlight in iceland by Grafixart Sam.

Grafixart Sam submitted this photo of Svartifoss (the Black Waterfall) on August 31, 2018. This glorious waterfall is located in Iceland’s Vatnajökull National Park, on Iceland’s south coast. It drops 65 feet (20 meters) and got its name because the cliff from which it falls is made of hexagonal black basalt columns, of a type found elsewhere in Iceland.

Here’s a great description of hiking to Svartifoss

Thank you, Grafixart Sam!

Svartifoss – the Black Waterfall – takes its name from the black basalt columns in the cliff from which it drops. Photo via GlacierGuides.

Bottom line: Photo of Svartifoss, in Iceland, under moonlight.



from EarthSky https://ift.tt/2C7Ac1n

Moon moves through Taurus the Bull

The next few early mornings – September 2 to 4, 2018 – look for the moon sweeping through the constellation Taurus the Bull. This is one of our sky’s most prominent constellations, an easy one to identify, even from small cities. If you’re a night owl, you might spot the moon and constellation Taurus above your eastern horizon before your bedtime.

But the view of the moon and Taurus is best before dawn, when they’ll be highest in the sky.

Let the moon guide your eye to the constellation Taurus’ two major signposts, the bright star Aldebaran in the V-shaped Face of the Bull and the tiny, dipper-shaped Pleiades star cluster, also known as the Seven Sisters.

Looking at dusk? Catch Venus, Jupiter and Arcturus

Although the moon will move out of Taurus after several more days, and will leave the morning sky in about a week, you can always use Orion’s Belt to star-hop to the star Aldebaran and the Pleiades cluster.

The three stars of Orion’s Belt always point to the star Aldebaran and the Pleiades star cluster. Image via Janne/Flickr.

From around the world on the morning of September 2, note that the lit side of the waning moon is pointing eastward, or in the direction of Aldebaran. Relative to the backdrop stars of the zodiac, the moon travels 1/2 degree (its own angular diameter) eastward per hour, or about 13 degrees (26 moon diameters) eastward per day. That’s because the moon, in its orbit, goes full circle in front of the constellations of the zodiac every month.

The feature sky chart above shows the sky scene for mid-northern North American latitudes. At this same time and date in the world’s Eastern Hemisphere, you’ll find the moon somewhat offset toward the previous date. In fact, as seen from Moscow, Russia, the moon will be pretty much due north of Aldebaran in the September 3 predawn/dawn sky.

The moon will occult – cover over – Aldebaran in the northernmost regions of the globe on September 3, 2018. This will be the final occultation in a series of 49 monthly occultations of Aldebaran that started on January 29, 2015.

From here on out, from everywhere worldwide, the moon will swing to the north of Aldebaran every month for nearly 15 years, or until the next series of 48 monthly occultations begins on August 18, 2033, and concludes on February 23, 2037.

Orion’s Belt, at the lower left, always points in the direction of the constellation Taurus the Bull. The star Aldebaran resides to the south of the ecliptic and the Pleiades star cluster to the north of the ecliptic.

Bottom line: Let the moon be your guide to the constellation Taurus the Bull in early September, 2018. Then use Orion’s Belt to locate Taurus when the moon moves away.



from EarthSky https://ift.tt/2ougX8w

The next few early mornings – September 2 to 4, 2018 – look for the moon sweeping through the constellation Taurus the Bull. This is one of our sky’s most prominent constellations, an easy one to identify, even from small cities. If you’re a night owl, you might spot the moon and constellation Taurus above your eastern horizon before your bedtime.

But the view of the moon and Taurus is best before dawn, when they’ll be highest in the sky.

Let the moon guide your eye to the constellation Taurus’ two major signposts, the bright star Aldebaran in the V-shaped Face of the Bull and the tiny, dipper-shaped Pleiades star cluster, also known as the Seven Sisters.

Looking at dusk? Catch Venus, Jupiter and Arcturus

Although the moon will move out of Taurus after several more days, and will leave the morning sky in about a week, you can always use Orion’s Belt to star-hop to the star Aldebaran and the Pleiades cluster.

The three stars of Orion’s Belt always point to the star Aldebaran and the Pleiades star cluster. Image via Janne/Flickr.

From around the world on the morning of September 2, note that the lit side of the waning moon is pointing eastward, or in the direction of Aldebaran. Relative to the backdrop stars of the zodiac, the moon travels 1/2 degree (its own angular diameter) eastward per hour, or about 13 degrees (26 moon diameters) eastward per day. That’s because the moon, in its orbit, goes full circle in front of the constellations of the zodiac every month.

The feature sky chart above shows the sky scene for mid-northern North American latitudes. At this same time and date in the world’s Eastern Hemisphere, you’ll find the moon somewhat offset toward the previous date. In fact, as seen from Moscow, Russia, the moon will be pretty much due north of Aldebaran in the September 3 predawn/dawn sky.

The moon will occult – cover over – Aldebaran in the northernmost regions of the globe on September 3, 2018. This will be the final occultation in a series of 49 monthly occultations of Aldebaran that started on January 29, 2015.

From here on out, from everywhere worldwide, the moon will swing to the north of Aldebaran every month for nearly 15 years, or until the next series of 48 monthly occultations begins on August 18, 2033, and concludes on February 23, 2037.

Orion’s Belt, at the lower left, always points in the direction of the constellation Taurus the Bull. The star Aldebaran resides to the south of the ecliptic and the Pleiades star cluster to the north of the ecliptic.

Bottom line: Let the moon be your guide to the constellation Taurus the Bull in early September, 2018. Then use Orion’s Belt to locate Taurus when the moon moves away.



from EarthSky https://ift.tt/2ougX8w