Our sky chart for the next few nights – January 8 and 9, 2020 – covers more area of sky than we typically show. It’s in answer to a reader in Nashville, who wrote:
I’ve heard mention of the Winter Circle of stars. Could you list the stars in this circle?
We can do better than that. We can advise you to go outside on this date, and look for the waxing gibbous moon, then notice the stars nearby. The moon is within the Winter Circle stars on this date. All the stars of the Winter Circle (sometimes called the Winter Hexagon) are first-magnitude stars, so they should be able to withstand tonight’s drenching moonlight.
This pattern of stars is not a constellation. It’s a lot of separate stars in different constellations. In other words, it’s what’s called an asterism. From our Northern Hemisphere locations, these same bright stars can be seen before dawn every late summer and early fall. And they can be seen in the evening every winter. Hence the name Winter Circle.
Are you familiar with the constellation Orion the Hunter? If so, this brilliant constellation makes up the southwest corner of the Winter Circle. And Orion’s bright star Betelgeuse forms an equilateral triangle with the stars Sirius and Procyon, which we in the Northern Hemisphere call the Winter Triangle.
I wonder what these same stars are called in the Southern Hemisphere? They’re visible from there, but of course it’s summer there now. I don’t know if this particular collection of bright stars has some special name as seen from that part of the globe. If any of you do know … tell us in the comments!
View larger. | This beautiful photo of the Winter Circle was taken on January 11, 2014, by EarthSky Facebook friend Duke Marsh in Indiana, when moon was near the star Aldebaran, and the planet Jupiter was in the vicinity of the Gemini stars, Castor and Pollux. Thank you, Duke.
Bottom line: The stars of the Winter Circle may be seen on these cold winter nights until well after midnight. On January 8, 2020, the moon is inside the Winter Circle.
Our sky chart for the next few nights – January 8 and 9, 2020 – covers more area of sky than we typically show. It’s in answer to a reader in Nashville, who wrote:
I’ve heard mention of the Winter Circle of stars. Could you list the stars in this circle?
We can do better than that. We can advise you to go outside on this date, and look for the waxing gibbous moon, then notice the stars nearby. The moon is within the Winter Circle stars on this date. All the stars of the Winter Circle (sometimes called the Winter Hexagon) are first-magnitude stars, so they should be able to withstand tonight’s drenching moonlight.
This pattern of stars is not a constellation. It’s a lot of separate stars in different constellations. In other words, it’s what’s called an asterism. From our Northern Hemisphere locations, these same bright stars can be seen before dawn every late summer and early fall. And they can be seen in the evening every winter. Hence the name Winter Circle.
Are you familiar with the constellation Orion the Hunter? If so, this brilliant constellation makes up the southwest corner of the Winter Circle. And Orion’s bright star Betelgeuse forms an equilateral triangle with the stars Sirius and Procyon, which we in the Northern Hemisphere call the Winter Triangle.
I wonder what these same stars are called in the Southern Hemisphere? They’re visible from there, but of course it’s summer there now. I don’t know if this particular collection of bright stars has some special name as seen from that part of the globe. If any of you do know … tell us in the comments!
View larger. | This beautiful photo of the Winter Circle was taken on January 11, 2014, by EarthSky Facebook friend Duke Marsh in Indiana, when moon was near the star Aldebaran, and the planet Jupiter was in the vicinity of the Gemini stars, Castor and Pollux. Thank you, Duke.
Bottom line: The stars of the Winter Circle may be seen on these cold winter nights until well after midnight. On January 8, 2020, the moon is inside the Winter Circle.
On January 7, 2020, a magnitude 6.4 earthquake struck Puerto Rico at 4:24 a.m. local time (08:24:26 UTC). Significant damage is possible. Over the past several weeks, hundreds of small earthquakes have occurred in the Puerto Rico region, beginning in earnest with a magnitude 4.7 earthquake late on December 28 and a magnitude 5.0 event a few hours later.
The magnitude 6.4 earthquake on January 7 was widely felt. According to ShakeMap, strong to very strong shaking occurred across parts of southern Puerto Rico, closest to the event, and moderate shaking occurred across the rest of the island. The NOAA Tsunami Warning System states no tsunami warning or advisory. The USGS summary page on this earthquake includes an aftershock forecast. Aftershocks will continue near the mainshock.
Since the magnitude 4.7 event on December 28, over 400 M 2+ earthquakes have occurred in this region, ten of which were magnitude 4+, including the January 7, 2020, 6.4 event and a January 6, 2020, 5.8 quake. The preliminary location of the January 7 6.4 earthquake is within about 7.5 miles (12 km) of the January 6, 2020, magnitude 5.8 earthquake. The proximity of these events to Puerto Rico, and their shallow depth, mean that dozens of these events have been felt on land, though with the exception of the latest two earthquakes, the magnitude 6.4 and the magnitude 5.8, none are likely to have caused significant damage.
The January 6 and 7, 2020, magnitude 5.8 and magnitude 6.4 earthquakes offshore of southwest Puerto Rico occurred as the result of oblique strike slip faulting at shallow depth. At the location of this event, the North America plate converges with the Caribbean plate at a rate of about 20 mm/yr towards the west-southwest. The location and style of faulting for the event is consistent with an intraplate tectonic setting within the upper crust of the Caribbean plate, rather than on the plate boundary between the two plates.
Tectonics in Puerto Rico are dominated by the convergence between the North America and Caribbean plates, with the island being squeezed between the two. To the north of Puerto Rico, North America subducts beneath the Caribbean plate along the Puerto Rico trench. To the south of the island, and south of today’s earthquake, Caribbean plate upper crust subducts beneath Puerto Rico at the Muertos Trough. The January 6 earthquake, and other recent nearby events, are occurring in the offshore deformation zone bound by the Punta Montalva Fault on land and the Guayanilla Canyon offshore.
Here are the largest earthquakes to impact Puerto Rico since yesterday
Visit the USGS event page for more information. For estimates of casualties and damage, visit the USGS Prompt Assessment of Global Earthquakes for Response (PAGER) website. If you felt any of these earthquakes, report your experience on the USGS Did You Feel It? website for this event.
USGS scientists expect that this event will trigger aftershocks, but these will decrease in frequency over time. You can view the aftershock forecast here.
On January 7, 2020, a magnitude 6.4 earthquake struck Puerto Rico at 4:24 a.m. local time (08:24:26 UTC). Significant damage is possible. Over the past several weeks, hundreds of small earthquakes have occurred in the Puerto Rico region, beginning in earnest with a magnitude 4.7 earthquake late on December 28 and a magnitude 5.0 event a few hours later.
The magnitude 6.4 earthquake on January 7 was widely felt. According to ShakeMap, strong to very strong shaking occurred across parts of southern Puerto Rico, closest to the event, and moderate shaking occurred across the rest of the island. The NOAA Tsunami Warning System states no tsunami warning or advisory. The USGS summary page on this earthquake includes an aftershock forecast. Aftershocks will continue near the mainshock.
Since the magnitude 4.7 event on December 28, over 400 M 2+ earthquakes have occurred in this region, ten of which were magnitude 4+, including the January 7, 2020, 6.4 event and a January 6, 2020, 5.8 quake. The preliminary location of the January 7 6.4 earthquake is within about 7.5 miles (12 km) of the January 6, 2020, magnitude 5.8 earthquake. The proximity of these events to Puerto Rico, and their shallow depth, mean that dozens of these events have been felt on land, though with the exception of the latest two earthquakes, the magnitude 6.4 and the magnitude 5.8, none are likely to have caused significant damage.
The January 6 and 7, 2020, magnitude 5.8 and magnitude 6.4 earthquakes offshore of southwest Puerto Rico occurred as the result of oblique strike slip faulting at shallow depth. At the location of this event, the North America plate converges with the Caribbean plate at a rate of about 20 mm/yr towards the west-southwest. The location and style of faulting for the event is consistent with an intraplate tectonic setting within the upper crust of the Caribbean plate, rather than on the plate boundary between the two plates.
Tectonics in Puerto Rico are dominated by the convergence between the North America and Caribbean plates, with the island being squeezed between the two. To the north of Puerto Rico, North America subducts beneath the Caribbean plate along the Puerto Rico trench. To the south of the island, and south of today’s earthquake, Caribbean plate upper crust subducts beneath Puerto Rico at the Muertos Trough. The January 6 earthquake, and other recent nearby events, are occurring in the offshore deformation zone bound by the Punta Montalva Fault on land and the Guayanilla Canyon offshore.
Here are the largest earthquakes to impact Puerto Rico since yesterday
Visit the USGS event page for more information. For estimates of casualties and damage, visit the USGS Prompt Assessment of Global Earthquakes for Response (PAGER) website. If you felt any of these earthquakes, report your experience on the USGS Did You Feel It? website for this event.
USGS scientists expect that this event will trigger aftershocks, but these will decrease in frequency over time. You can view the aftershock forecast here.
Artist’s concept of the three “super-puff” giant planets orbiting the star Kepler-51. Image via NASA/ ESA/ L. Hustak/ J. Olmsted/ D. Player/ F. Summers (STScI)/ Hubblesite.
Exoplanets – planets orbiting distant stars – come in a wide variety of sizes, masses and compositions. Most found so far bear at least some resemblance to planets in our own solar system, either large and gaseous or smaller and rocky. Variations, so far anyway, have been more or less based on those two general themes. But another, more enigmatic and exotic type of planet has been discovered, which looks like nothing in our solar system. Astronomers call them super-puff” planets or cotton candy planets. They’re more lightweight (less dense) than any planets seen before.
A few of them have been known about since 2014, but researchers have now been able to take a closer look at three of these planets, orbiting the sun-like star Kepler-51, which is estimated to be 2,600 light-years away. The intriguing findings were made and announced by scientists working with the Hubble Space Telescope. The new peer-reviewed paper will be published soon in The Astronomical Journal.
These bizarre worlds are nearly the size of Jupiter, yet they are only 1/100th as massive.
Artist’s impression of the 3 known Kepler-51 planets in contrast to some of the planets in our own solar system. Image via NASA/ ESA/ STScI/ CU Boulder Today.
Simply put, these planets are weird. As astronomer Jessica Libby-Roberts at the University of Colorado Boulder – who led the new study – stated:
This is an extreme example of what’s so cool about exoplanets in general. They give us an opportunity to study worlds that are very different than ours, but they also place the planets in our own solar system into a larger context.
The three planets orbiting Kepler-51 were first discovered in 2014, and fewer than 15 super-puff or cotton candy planets have been found in total so far. According to Berta-Thompson:
Their discovery was straight-up contrary to what we teach in undergraduate classrooms.
Cotton candy in space … do these planets actually look like this? No, they’re round like other planets. But their extremely lightweight composition is analogous to the lightness and fluffiness the popular carnival treat of spun sugar. Image via CU Boulder Today.
The super-puff or cotton candy planets were found to have much lower densities than anything in our solar system, less than 0.1 grams per cubic centimeter of volume – almost identical to cotton candy, hence the nickname. Even lightweight Saturn, which could theoretically float in water, is still a lot denser than these worlds. As Libby-Roberts said:
We knew they were low density. But when you picture a Jupiter-sized ball of cotton candy – that’s really low density.
The researchers wanted to study the planets’ atmospheres. But instead of having transparent atmospheres, the planets were found to be enshrouded by opaque haze or clouds. Libby-Roberts said:
It definitely sent us scrambling to come up with what could be going on here. We expected to find water, but we couldn’t observe the signatures of any molecule.
The gas giant planet Saturn as seen at equinox by the Cassini spacecraft. Its density is so low that it could, theoretically, float in water. But the super-puff planets have even lower densities than that. Image via NASA/ JPL/ Space Science Institute/ The Atlantic.
The planets seem to be composed mostly of the lightweight gases hydrogen and helium, covered by a thick layer of methane haze. This would make their atmospheres resemble that of Saturn’s moon Titan, which is also enshrouded by a thick methane haze. Libby-Roberts added:
If you hit methane with ultraviolet light, it will form a haze. It’s Titan in a nutshell.
But the researchers noticed something else about these planets, too. They are rapidly – cosmologically speaking, anyway – losing material to space. This means that they may not retain their cotton candy-like characteristics for any longer than the next billion years or so, as they continue to shrink in size. The innermost of the planets is losing billions of tons of material into space every second. Eventually, these worlds may look more like mini-Neptunes, so they may simply be in a transitory phase of planetary evolution. Libby-Roberts said:
People have been really struggling to find out why this system looks so different than every other system. We’re trying to show that, actually, it does look like some of these other systems.
Berta-Thompson added:
A good bit of their weirdness is coming from the fact that we’re seeing them at a time in their development where we’ve rarely gotten the chance to observe planets. This system offers a unique laboratory for testing theories of early planet evolution.
Jessica Libby-Roberts at the University of Colorado Boulder led the new study. Image via University of Colorado Boulder.
Scientists still want to determine these planets’ actual atmospheric compositions. NASA’s upcoming James Webb Space Telescope may be able to do that, since its sensitivity to longer wavelengths of light means it could possibly peer through the deep cloud layers. Until then, these planets are a tantalizing mystery, providing new clues as to how planets evolve, even the similar – but not quite as lightweight – giant planets in our own solar system.
Bottom line: New observations of “super-puff” exoplanets by the Hubble Space Telescope have provided scientists with more clues about these enigmatic and strange worlds.
Artist’s concept of the three “super-puff” giant planets orbiting the star Kepler-51. Image via NASA/ ESA/ L. Hustak/ J. Olmsted/ D. Player/ F. Summers (STScI)/ Hubblesite.
Exoplanets – planets orbiting distant stars – come in a wide variety of sizes, masses and compositions. Most found so far bear at least some resemblance to planets in our own solar system, either large and gaseous or smaller and rocky. Variations, so far anyway, have been more or less based on those two general themes. But another, more enigmatic and exotic type of planet has been discovered, which looks like nothing in our solar system. Astronomers call them super-puff” planets or cotton candy planets. They’re more lightweight (less dense) than any planets seen before.
A few of them have been known about since 2014, but researchers have now been able to take a closer look at three of these planets, orbiting the sun-like star Kepler-51, which is estimated to be 2,600 light-years away. The intriguing findings were made and announced by scientists working with the Hubble Space Telescope. The new peer-reviewed paper will be published soon in The Astronomical Journal.
These bizarre worlds are nearly the size of Jupiter, yet they are only 1/100th as massive.
Artist’s impression of the 3 known Kepler-51 planets in contrast to some of the planets in our own solar system. Image via NASA/ ESA/ STScI/ CU Boulder Today.
Simply put, these planets are weird. As astronomer Jessica Libby-Roberts at the University of Colorado Boulder – who led the new study – stated:
This is an extreme example of what’s so cool about exoplanets in general. They give us an opportunity to study worlds that are very different than ours, but they also place the planets in our own solar system into a larger context.
The three planets orbiting Kepler-51 were first discovered in 2014, and fewer than 15 super-puff or cotton candy planets have been found in total so far. According to Berta-Thompson:
Their discovery was straight-up contrary to what we teach in undergraduate classrooms.
Cotton candy in space … do these planets actually look like this? No, they’re round like other planets. But their extremely lightweight composition is analogous to the lightness and fluffiness the popular carnival treat of spun sugar. Image via CU Boulder Today.
The super-puff or cotton candy planets were found to have much lower densities than anything in our solar system, less than 0.1 grams per cubic centimeter of volume – almost identical to cotton candy, hence the nickname. Even lightweight Saturn, which could theoretically float in water, is still a lot denser than these worlds. As Libby-Roberts said:
We knew they were low density. But when you picture a Jupiter-sized ball of cotton candy – that’s really low density.
The researchers wanted to study the planets’ atmospheres. But instead of having transparent atmospheres, the planets were found to be enshrouded by opaque haze or clouds. Libby-Roberts said:
It definitely sent us scrambling to come up with what could be going on here. We expected to find water, but we couldn’t observe the signatures of any molecule.
The gas giant planet Saturn as seen at equinox by the Cassini spacecraft. Its density is so low that it could, theoretically, float in water. But the super-puff planets have even lower densities than that. Image via NASA/ JPL/ Space Science Institute/ The Atlantic.
The planets seem to be composed mostly of the lightweight gases hydrogen and helium, covered by a thick layer of methane haze. This would make their atmospheres resemble that of Saturn’s moon Titan, which is also enshrouded by a thick methane haze. Libby-Roberts added:
If you hit methane with ultraviolet light, it will form a haze. It’s Titan in a nutshell.
But the researchers noticed something else about these planets, too. They are rapidly – cosmologically speaking, anyway – losing material to space. This means that they may not retain their cotton candy-like characteristics for any longer than the next billion years or so, as they continue to shrink in size. The innermost of the planets is losing billions of tons of material into space every second. Eventually, these worlds may look more like mini-Neptunes, so they may simply be in a transitory phase of planetary evolution. Libby-Roberts said:
People have been really struggling to find out why this system looks so different than every other system. We’re trying to show that, actually, it does look like some of these other systems.
Berta-Thompson added:
A good bit of their weirdness is coming from the fact that we’re seeing them at a time in their development where we’ve rarely gotten the chance to observe planets. This system offers a unique laboratory for testing theories of early planet evolution.
Jessica Libby-Roberts at the University of Colorado Boulder led the new study. Image via University of Colorado Boulder.
Scientists still want to determine these planets’ actual atmospheric compositions. NASA’s upcoming James Webb Space Telescope may be able to do that, since its sensitivity to longer wavelengths of light means it could possibly peer through the deep cloud layers. Until then, these planets are a tantalizing mystery, providing new clues as to how planets evolve, even the similar – but not quite as lightweight – giant planets in our own solar system.
Bottom line: New observations of “super-puff” exoplanets by the Hubble Space Telescope have provided scientists with more clues about these enigmatic and strange worlds.
View at EarthSky Community Photos. | Brian Ottum kindly provided this direct comparison of Betelgeuse a few years ago and Betelgeuse now. He wrote: “Left is February 2016. Right is December 31, 2019. Note that the brightness/appearance of all background stars are identical left versus right, but Betelgeuse is definitely fainter on the right.” Thank you, Brian!
Why is the red supergiant star Betelgeuse in the news?
Beginning in October 2019, astronomers noticed that the brightness of Betelgeuse suddenly began to change. The star was dimming. Once one of the top 10 brightest stars in the sky, its brightness had fallen to 21st place by the end of December 2019. Wild claims have been made about this sudden dimming of Betelgeuse, and many misconceptions spread. Some media outlets claimed the dimming was evidence that the star was about to go supernova, ending its life in a spectacular explosion. Is that possible? And if Betelgeuse did go supernova, how would that affect Earth?
Betelgeuse is one of 2 very bright stars in the constellation Orion. The other bright star is Rigel. Notice Betelgeuse and Rigel on either side of the short, straight row of three medium-bright stars. That row of stars represents Orion’s Belt. Betelgeuse represents Orion’s Shoulder.
What is Betelgeuse?
Betelgeuse, pronounced “BET-tal-joos”, is a red supergiant star, located an estimated 642 light-years away. It’s the alpha star – that is the brightest star – of the constellation Orion the Hunter, which is a very prominent constellation in the sky at this time of year. Betelgeuse represents Orion’s left shoulder. It’s a distinctly red-colored star. Betelgeuse has an estimated diameter of 767 million miles (about 1,200 km), as befits a red supergiant star. It has an estimated mass nearly 12 times that of our sun. The star is estimated to be between nine and ten million years old, in contrast to our sun’s age of about 4.5 billion years. Yet our sun is only middle-aged, while Betelgeuse is nearing the end of its life. That’s because the massive supergiant stars, like Betelgeuse, burn their thermonuclear fuel more quickly that medium-sized stars like our sun.
This image, made with the Atacama Large Millimeter/submillimeter Array (ALMA), shows the red supergiant Betelgeuse, one of the largest stars known. In the millimeter part of the spectrum the star is around 1,400 times larger than our sun. The overlaid annotation shows how large the star is compared to our solar system. Betelgeuse would engulf all four terrestrial planets — Mercury, Venus, Earth and Mars — and even the gas giant Jupiter. Only Saturn would be beyond its surface. Image via ESO.
Is Betelgeuse’ dimming unusual? Will the star go supernova?
The dimming of Betelgeuse is not unusual per se. It has been known for a long time that Betelgeuse is a variable star, that is to say one whose brightness fluctuates over time. The star has been found to have multiple cycles of dimming: a 5.9-year main cycle and, within that, several smaller ones. It’s conceivable that – when the minima of all the cycles come together – the star could look exceptionally faint, as it does now.
And there are other possibilities. Astronomers have also suggested that the change in brightness could be due to some sort of eruption of gas or dust, or changes in the star’s surface brightness.
So will Betelgeuse go supernova? Yes! But probably not in our lifetimes. Current understanding is that all supergiants, be they red or blue, end their lives as supernovae. However, in the case of Betelgeuse, this event is predicted to happen anytime within the next few hundred thousand years.
Most astronomers do not believe a supernova is imminent. For example, astronomers Richard Wasatonic and Edward Guinan, of Villanova University, postulate that the current dimming is due to an unusually extreme 425-day dimming cycle within the main 5.9-year one. Unusual, certainly, but nothing that indicates an imminent explosion.
The other thing to remember is that there is no precedent, in astronomy’s history of observing supernovae, for the end of a supergiant star’s life to be preceded by a dimming of its light. Such a phenomenon has not been observed, although it cannot be ruled out. But certainly there is nothing in the computer models of supernovae to indicate the existence of a dimming phase before the explosion.
It must be said, however, that predicting supernovae is very much an inexact science, so there is still a possibility, however remote, that Betelguese’s fiery end could indeed happen tomorrow. Or, to be more exact, it happened 642 years ago and the light from it is about to reach the Earth.
Just had a look at #Betelgeuse a few days ago seemed similar or just a little fraction brighter than Bellatrix, though in moonlight it seemed a bit brighter? circa ~1.4m. I will wait until the moon has moved away in a week or so then will look again.
If Betelgeuse did go supernova, is the Earth in any danger?
No. Our planet is simply too far away from Betelgeuse for the supernova to present any danger whatsoever. It will have absolutely no effect on the solar system. Stories you might have read in the media, about our planet being in danger, are just hype.
Astronomers believe the dimming cycle will end soon and Betelgeuse will return to its former glory. As its brightness increases, it is certain that the stories in the media about the star will fade and this episode will swiftly be forgotten.
However, one day Betelgeuse will explode and give us an amazing celestial show. It’ll be brighter in our sky than a full moon, and possibly visible in daytime!
This is what the star Betelgeuse exploding would look like from Earth.
Bottom line: Questions and answers about the recent dimming of the star Betelgeuse.
from EarthSky https://ift.tt/2T1VIvo
View at EarthSky Community Photos. | Brian Ottum kindly provided this direct comparison of Betelgeuse a few years ago and Betelgeuse now. He wrote: “Left is February 2016. Right is December 31, 2019. Note that the brightness/appearance of all background stars are identical left versus right, but Betelgeuse is definitely fainter on the right.” Thank you, Brian!
Why is the red supergiant star Betelgeuse in the news?
Beginning in October 2019, astronomers noticed that the brightness of Betelgeuse suddenly began to change. The star was dimming. Once one of the top 10 brightest stars in the sky, its brightness had fallen to 21st place by the end of December 2019. Wild claims have been made about this sudden dimming of Betelgeuse, and many misconceptions spread. Some media outlets claimed the dimming was evidence that the star was about to go supernova, ending its life in a spectacular explosion. Is that possible? And if Betelgeuse did go supernova, how would that affect Earth?
Betelgeuse is one of 2 very bright stars in the constellation Orion. The other bright star is Rigel. Notice Betelgeuse and Rigel on either side of the short, straight row of three medium-bright stars. That row of stars represents Orion’s Belt. Betelgeuse represents Orion’s Shoulder.
What is Betelgeuse?
Betelgeuse, pronounced “BET-tal-joos”, is a red supergiant star, located an estimated 642 light-years away. It’s the alpha star – that is the brightest star – of the constellation Orion the Hunter, which is a very prominent constellation in the sky at this time of year. Betelgeuse represents Orion’s left shoulder. It’s a distinctly red-colored star. Betelgeuse has an estimated diameter of 767 million miles (about 1,200 km), as befits a red supergiant star. It has an estimated mass nearly 12 times that of our sun. The star is estimated to be between nine and ten million years old, in contrast to our sun’s age of about 4.5 billion years. Yet our sun is only middle-aged, while Betelgeuse is nearing the end of its life. That’s because the massive supergiant stars, like Betelgeuse, burn their thermonuclear fuel more quickly that medium-sized stars like our sun.
This image, made with the Atacama Large Millimeter/submillimeter Array (ALMA), shows the red supergiant Betelgeuse, one of the largest stars known. In the millimeter part of the spectrum the star is around 1,400 times larger than our sun. The overlaid annotation shows how large the star is compared to our solar system. Betelgeuse would engulf all four terrestrial planets — Mercury, Venus, Earth and Mars — and even the gas giant Jupiter. Only Saturn would be beyond its surface. Image via ESO.
Is Betelgeuse’ dimming unusual? Will the star go supernova?
The dimming of Betelgeuse is not unusual per se. It has been known for a long time that Betelgeuse is a variable star, that is to say one whose brightness fluctuates over time. The star has been found to have multiple cycles of dimming: a 5.9-year main cycle and, within that, several smaller ones. It’s conceivable that – when the minima of all the cycles come together – the star could look exceptionally faint, as it does now.
And there are other possibilities. Astronomers have also suggested that the change in brightness could be due to some sort of eruption of gas or dust, or changes in the star’s surface brightness.
So will Betelgeuse go supernova? Yes! But probably not in our lifetimes. Current understanding is that all supergiants, be they red or blue, end their lives as supernovae. However, in the case of Betelgeuse, this event is predicted to happen anytime within the next few hundred thousand years.
Most astronomers do not believe a supernova is imminent. For example, astronomers Richard Wasatonic and Edward Guinan, of Villanova University, postulate that the current dimming is due to an unusually extreme 425-day dimming cycle within the main 5.9-year one. Unusual, certainly, but nothing that indicates an imminent explosion.
The other thing to remember is that there is no precedent, in astronomy’s history of observing supernovae, for the end of a supergiant star’s life to be preceded by a dimming of its light. Such a phenomenon has not been observed, although it cannot be ruled out. But certainly there is nothing in the computer models of supernovae to indicate the existence of a dimming phase before the explosion.
It must be said, however, that predicting supernovae is very much an inexact science, so there is still a possibility, however remote, that Betelguese’s fiery end could indeed happen tomorrow. Or, to be more exact, it happened 642 years ago and the light from it is about to reach the Earth.
Just had a look at #Betelgeuse a few days ago seemed similar or just a little fraction brighter than Bellatrix, though in moonlight it seemed a bit brighter? circa ~1.4m. I will wait until the moon has moved away in a week or so then will look again.
If Betelgeuse did go supernova, is the Earth in any danger?
No. Our planet is simply too far away from Betelgeuse for the supernova to present any danger whatsoever. It will have absolutely no effect on the solar system. Stories you might have read in the media, about our planet being in danger, are just hype.
Astronomers believe the dimming cycle will end soon and Betelgeuse will return to its former glory. As its brightness increases, it is certain that the stories in the media about the star will fade and this episode will swiftly be forgotten.
However, one day Betelgeuse will explode and give us an amazing celestial show. It’ll be brighter in our sky than a full moon, and possibly visible in daytime!
This is what the star Betelgeuse exploding would look like from Earth.
What is a lunar month? It’s simply the duration between successive new moons. Also called a lunation or synodic month, it has a mean period of 29.53059 days (29 days 12 hours and 44 minutes). That’s the mean, but the the true length varies throughout the year.
The longest lunar month in 2020 starts with the new moon on February 23, and concludes with the new moon on March 24. Its duration will be 29 days 17 hours and 56 minutes.
The shortest lunar month of 2020 starts with the August 19 new moon and ends with the new moon on September 17, lasting 29 days 8 hours and 19 minutes.
This year’s longest lunar month (January 24 to February 23) is 5 hours and 12 minutes longer than the mean lunar month, and the shortest lunar month (August 19 to September 17) is 4 hours and 25 minutes shorter than the mean lunar month.
Added all up, the duration of the year’s longest lunar month is 9 hours and 37 minutes greater than that of the shortest lunar month.
One lunar month is the period of time from new moon to new moon. As viewed from the north side of the Earth’s and moon’s orbital planes, the Earth goes counterclockwise around the sun and the moon goes counterclockwise around Earth. Image via Wikipedia.
Why are the lunar months different lengths? In a nutshell, the longest lunar month occurs when the successive new moons coincide closely with lunar apogee – the moon’s farthest point from Earth in its orbit.
In contrast, the year’s shortest lunar month takes place when the successive new moons fall appreciably close to lunar perigee – the moon’s closest point to Earth in its orbit.
On the average, the lunar month (new moon to new moon) is about 2.22 days longer than the sidereal month (one complete revolution of the moon relative to the background stars). However, if the moon is near apogee at the end of one sidereal month, the moon travels more slowly than average in its orbit. Therefore, the period of time between the end of the sidereal month and the end of the lunar month is longer than average.
The opposite is the case when the moon is near perigee. The moon travels more swiftly in its orbit at perigee, in which case the time period between the end of the sidereal month and the end of the lunar month is less than average.
The most extreme longest lunar months happen when successive new moons occur near lunar apogee – and in addition, when Earth is near perihelion (its closest point to the sun). Because Earth is always closest to the sun in early January, the very longest lunar months take place between December and January new moons.
On the other hand, extremely short lunar months happen when successive new moons fall near lunar perigee – and in addition, the Earth is near aphelion (Earth’s farthest point from the sun in its orbit). Because Earth is always at aphelion in early July, the very shortest lunar months take place between June and July new moons.
The variation in the length of lunar months happens because the moon’s orbit around Earth is not a perfect circle. However, it is very nearly circular, as the above diagram shows. Diagram by Brian Koberlein.
When are the longest and shortest lunar months of the 21st century? The longest lunar month of the 21st century (2001 to 2100) occurs between the December 2017 and January 2018 new moons. With a length of 29 days 19 hours and 47 minutes, this particular lunar month exceeds the mean by a whopping 7 hours and 3 minutes.
The century’s shortest lunar month takes place between the new moons of June and July 2053, a period of 29 days 6 hours and 35 minutes. That’s 6 hours and 9 minutes shorter than the mean.
Incidentally, exceptionally long or short lunar months repeat in cycles of 9 years.
Phases of the moon, posted to EarthSky Facebook by our friend Jacob Baker.
Bottom line: In 2020, the shortest lunar month happens between the August 19 and September 17 new moons; and the longest one between the February 23 and March 24 new moons. See Astropixel.com’s complete list of the length of each lunar month in the 21st century.
from EarthSky https://ift.tt/2FugP1m
Simulated view of the moon’s phases.
What is a lunar month? It’s simply the duration between successive new moons. Also called a lunation or synodic month, it has a mean period of 29.53059 days (29 days 12 hours and 44 minutes). That’s the mean, but the the true length varies throughout the year.
The longest lunar month in 2020 starts with the new moon on February 23, and concludes with the new moon on March 24. Its duration will be 29 days 17 hours and 56 minutes.
The shortest lunar month of 2020 starts with the August 19 new moon and ends with the new moon on September 17, lasting 29 days 8 hours and 19 minutes.
This year’s longest lunar month (January 24 to February 23) is 5 hours and 12 minutes longer than the mean lunar month, and the shortest lunar month (August 19 to September 17) is 4 hours and 25 minutes shorter than the mean lunar month.
Added all up, the duration of the year’s longest lunar month is 9 hours and 37 minutes greater than that of the shortest lunar month.
One lunar month is the period of time from new moon to new moon. As viewed from the north side of the Earth’s and moon’s orbital planes, the Earth goes counterclockwise around the sun and the moon goes counterclockwise around Earth. Image via Wikipedia.
Why are the lunar months different lengths? In a nutshell, the longest lunar month occurs when the successive new moons coincide closely with lunar apogee – the moon’s farthest point from Earth in its orbit.
In contrast, the year’s shortest lunar month takes place when the successive new moons fall appreciably close to lunar perigee – the moon’s closest point to Earth in its orbit.
On the average, the lunar month (new moon to new moon) is about 2.22 days longer than the sidereal month (one complete revolution of the moon relative to the background stars). However, if the moon is near apogee at the end of one sidereal month, the moon travels more slowly than average in its orbit. Therefore, the period of time between the end of the sidereal month and the end of the lunar month is longer than average.
The opposite is the case when the moon is near perigee. The moon travels more swiftly in its orbit at perigee, in which case the time period between the end of the sidereal month and the end of the lunar month is less than average.
The most extreme longest lunar months happen when successive new moons occur near lunar apogee – and in addition, when Earth is near perihelion (its closest point to the sun). Because Earth is always closest to the sun in early January, the very longest lunar months take place between December and January new moons.
On the other hand, extremely short lunar months happen when successive new moons fall near lunar perigee – and in addition, the Earth is near aphelion (Earth’s farthest point from the sun in its orbit). Because Earth is always at aphelion in early July, the very shortest lunar months take place between June and July new moons.
The variation in the length of lunar months happens because the moon’s orbit around Earth is not a perfect circle. However, it is very nearly circular, as the above diagram shows. Diagram by Brian Koberlein.
When are the longest and shortest lunar months of the 21st century? The longest lunar month of the 21st century (2001 to 2100) occurs between the December 2017 and January 2018 new moons. With a length of 29 days 19 hours and 47 minutes, this particular lunar month exceeds the mean by a whopping 7 hours and 3 minutes.
The century’s shortest lunar month takes place between the new moons of June and July 2053, a period of 29 days 6 hours and 35 minutes. That’s 6 hours and 9 minutes shorter than the mean.
Incidentally, exceptionally long or short lunar months repeat in cycles of 9 years.
Phases of the moon, posted to EarthSky Facebook by our friend Jacob Baker.
Bottom line: In 2020, the shortest lunar month happens between the August 19 and September 17 new moons; and the longest one between the February 23 and March 24 new moons. See Astropixel.com’s complete list of the length of each lunar month in the 21st century.
Anthropologist Russell Ciochon in his lab at the University of Iowa, holding a cast of a Homo erectus skull. The original fossils are in Indonesia. Image via Russell Ciochon/ University of Iowa.
Scientists have determined the last known dates that Homo erectus, an early ancestor of human beings, walked the Earth. New analysis of a site at Ngandong, on the Indonesian island of Java, indicates that a population lived there as recently as 108,000 to 117,000 years ago. On December 18, 2019, the University of Iowa published a good description of this new study, which was led by Yan Rizal of the Bandung Institute of Technology, located in Bandung, Indonesia. The findings were published the same day in the peer-reviewed journal Nature.
Anthropologist Russell Ciochon of University of Iowa was a co-corresponding author on the study. Ciochon explained:
This site is the last known appearance of Homo erectus found anywhere in the world. We can’t say we dated the extinction, but we dated the last occurrence of it. We have no evidence Homo erectus lived later than that anywhere else.
The approximate location of Ngandong on the Indonesian island of Java in Southeast Asia. (Indonesia is shaded yellow in this map.) Map of Indonesia via Uwe Dedering/ Wikimedia Commons.
Homo erectus arose in Africa about 2 million years ago, then dispersed throughout Asia and perhaps Europe. By about 400,000 years ago, this early relative of modern humans had largely disappeared. The date range for the last known Homo erectus holdout, in Ngandong, is 108,000 to 117,000 years ago. Around that same time, modern humans were roaming in Africa, and Neanderthals lived in Europe.
The fossils in Ngandong had been discovered in the 1930s by Dutch surveyors. Using notes left by these early surveyors, the researchers on the new study relocated the original bone bed where the Homo erectus fossils (12 skull caps and two tibia) had been found. In 2008 and 2010, the team excavated that site to collect animal fossil fragments for dating.
The new age ranges for the Homo erectus fossils – 108,000 to 117,000 years old – were determined using two strategies; besides dating the animal fossils in the original bone bed, the scientists further constrained the date range by geological dating of river terraces below and above the fossil bed.
Dutch surveyors excavated the original bone bed containing Homo erectus fossils in the 1930s. In 2008 and 2010, researchers led by Yan Rizal located and found the same site, using the earlier study’s notes. Dating of animal fossils at that site were used, in part, to determine the new age of the Homo erectus fossils. Image via Russell Ciochon/ University of Iowa.
Around the same time that Yan Rizal’s team was excavating its site, another team, led by Kira Westaway of Macquarie University, was independently dating nearby surrounding landforms. Ciochon explained:
It was coincidental. With the data we had, we couldn’t really date the Ngandong fossils. We had dates on them, but they were minimum ages. So, we couldn’t really say how old, although we knew we were in the ballpark. By working with Kira, who had vast amount of dating data for the terraces, mountains, and other landscape features, we were able to provide precise regional chronological and geomorphic contexts for the Ngandong site.
Stalagmites from caves in the Southern Mountains of Ngandong were dated by Westaway’s team to determine when those mountains first rose. That helped them figure out when the Solo River started flowing through the fossil site and when sequences of river terraces were created. Westaway, who is listed as second author on the December 18, 2019, Naturepaper, said:
The issues with the dating of Ngandong could only ever be resolved by an appreciation of the wider landscape. Fossils are the byproducts of complex landscape processes. We were able to nail the age of the site because we constrained the fossils within the river deposit, the river terrace, the sequence of terraces, and the volcanically active landscape.
Ciochon commented on the 52 new age estimates arrived at by the team:
You have this incredible array of dates that are all consistent. This has to be the right range. That’s why it’s such a nice, tight paper. The dating is very consistent.
According to previous research by Ciochon and others, Homo erectus arrived at Java, Indonesia, about 1.6 million years ago, and settled across the Indonesian islands. Back then, Ngandong was mainly a grassland with a rich flora and fauna, not unlike Homo erectus‘ original habitat in Africa. But around 130,000 years ago, it changed. Ciochon explained:
There was a change in climate. We know the fauna changed from open country, grassland, to a tropical rainforest (extending southward from today’s Malaysia). Those were not the plants and animals that Homo erectus was used to, and the species just could not adapt.
Ciochon also remarked on a unique feature of the Ngandong Homo erectus population. In a video statement, he said:
We assume that Homo erectus on the island of Java, because it was isolated, continued to encephalize – the brain got bigger. Does that mean that Homo erectus on Java was smarter than Homo erectus in Africa? We don’t know. But we can certainly document that the brain got bigger.
Casts of Homo erectus skulls at Russell Ciochon’s lab. Via Russell Ciochon/ University of Iowa.
Bottom line: The last known Homo erectus, a human ancestor, lived in Ngandong, Java, as recently as 108,000 to 117,000 years ago. These findings, published in the December 18, 2019, issue of Nature, are based on dating fossilized animals from the same bone bed in which the Homo erectus remains were found in the 1930s, and also by dating river terraces at the fossil site.
Anthropologist Russell Ciochon in his lab at the University of Iowa, holding a cast of a Homo erectus skull. The original fossils are in Indonesia. Image via Russell Ciochon/ University of Iowa.
Scientists have determined the last known dates that Homo erectus, an early ancestor of human beings, walked the Earth. New analysis of a site at Ngandong, on the Indonesian island of Java, indicates that a population lived there as recently as 108,000 to 117,000 years ago. On December 18, 2019, the University of Iowa published a good description of this new study, which was led by Yan Rizal of the Bandung Institute of Technology, located in Bandung, Indonesia. The findings were published the same day in the peer-reviewed journal Nature.
Anthropologist Russell Ciochon of University of Iowa was a co-corresponding author on the study. Ciochon explained:
This site is the last known appearance of Homo erectus found anywhere in the world. We can’t say we dated the extinction, but we dated the last occurrence of it. We have no evidence Homo erectus lived later than that anywhere else.
The approximate location of Ngandong on the Indonesian island of Java in Southeast Asia. (Indonesia is shaded yellow in this map.) Map of Indonesia via Uwe Dedering/ Wikimedia Commons.
Homo erectus arose in Africa about 2 million years ago, then dispersed throughout Asia and perhaps Europe. By about 400,000 years ago, this early relative of modern humans had largely disappeared. The date range for the last known Homo erectus holdout, in Ngandong, is 108,000 to 117,000 years ago. Around that same time, modern humans were roaming in Africa, and Neanderthals lived in Europe.
The fossils in Ngandong had been discovered in the 1930s by Dutch surveyors. Using notes left by these early surveyors, the researchers on the new study relocated the original bone bed where the Homo erectus fossils (12 skull caps and two tibia) had been found. In 2008 and 2010, the team excavated that site to collect animal fossil fragments for dating.
The new age ranges for the Homo erectus fossils – 108,000 to 117,000 years old – were determined using two strategies; besides dating the animal fossils in the original bone bed, the scientists further constrained the date range by geological dating of river terraces below and above the fossil bed.
Dutch surveyors excavated the original bone bed containing Homo erectus fossils in the 1930s. In 2008 and 2010, researchers led by Yan Rizal located and found the same site, using the earlier study’s notes. Dating of animal fossils at that site were used, in part, to determine the new age of the Homo erectus fossils. Image via Russell Ciochon/ University of Iowa.
Around the same time that Yan Rizal’s team was excavating its site, another team, led by Kira Westaway of Macquarie University, was independently dating nearby surrounding landforms. Ciochon explained:
It was coincidental. With the data we had, we couldn’t really date the Ngandong fossils. We had dates on them, but they were minimum ages. So, we couldn’t really say how old, although we knew we were in the ballpark. By working with Kira, who had vast amount of dating data for the terraces, mountains, and other landscape features, we were able to provide precise regional chronological and geomorphic contexts for the Ngandong site.
Stalagmites from caves in the Southern Mountains of Ngandong were dated by Westaway’s team to determine when those mountains first rose. That helped them figure out when the Solo River started flowing through the fossil site and when sequences of river terraces were created. Westaway, who is listed as second author on the December 18, 2019, Naturepaper, said:
The issues with the dating of Ngandong could only ever be resolved by an appreciation of the wider landscape. Fossils are the byproducts of complex landscape processes. We were able to nail the age of the site because we constrained the fossils within the river deposit, the river terrace, the sequence of terraces, and the volcanically active landscape.
Ciochon commented on the 52 new age estimates arrived at by the team:
You have this incredible array of dates that are all consistent. This has to be the right range. That’s why it’s such a nice, tight paper. The dating is very consistent.
According to previous research by Ciochon and others, Homo erectus arrived at Java, Indonesia, about 1.6 million years ago, and settled across the Indonesian islands. Back then, Ngandong was mainly a grassland with a rich flora and fauna, not unlike Homo erectus‘ original habitat in Africa. But around 130,000 years ago, it changed. Ciochon explained:
There was a change in climate. We know the fauna changed from open country, grassland, to a tropical rainforest (extending southward from today’s Malaysia). Those were not the plants and animals that Homo erectus was used to, and the species just could not adapt.
Ciochon also remarked on a unique feature of the Ngandong Homo erectus population. In a video statement, he said:
We assume that Homo erectus on the island of Java, because it was isolated, continued to encephalize – the brain got bigger. Does that mean that Homo erectus on Java was smarter than Homo erectus in Africa? We don’t know. But we can certainly document that the brain got bigger.
Casts of Homo erectus skulls at Russell Ciochon’s lab. Via Russell Ciochon/ University of Iowa.
Bottom line: The last known Homo erectus, a human ancestor, lived in Ngandong, Java, as recently as 108,000 to 117,000 years ago. These findings, published in the December 18, 2019, issue of Nature, are based on dating fossilized animals from the same bone bed in which the Homo erectus remains were found in the 1930s, and also by dating river terraces at the fossil site.
These next three nights – January 6, 7 and 8, 2020 – the bright waxing gibbous moon shines in front of the constellation Taurus the Bull. However, it will be difficult to envision the starlit figure of the Bull on these moonlit nights. Despite the lunar glare, you might see this constellation’s two major signposts: the star Aldebaran and the Pleiades star cluster, otherwise known as the Seven Sisters.
Fred Espenak – Mr. Eclipse – posted this image at EarthSky Facebook. This image is a stack of 20 individual 5-minute exposures through a Takahashi Epsilon 180ED Hyperbolic Astrograph using a Canon 6D DSLR. Photo via MrEclipse.com.
During the moon’s trek through Taurus, the moon passes to the south of the Pleiades and then to the north of Aldebaran. In fact, each month for many years to come, the moon will pass to the south of the Pleiades and to the north of Aldebaran. Yet, month by month, the moon will travel farther north in front of Taurus, until it goes so far north that it stages a series of 79 lunar occultations of Alcyone (the Pleiades’ brightest star) from September 5, 2023, until July 7, 2029.
Once the moon drops out of the evening sky, you can use the three stars of Orion’s Belt to find the star Aldebaran and the Pleiades star cluster. Image via Janne/Flickr.
What’s more, starting on September 7, 2023 (only two days after the initial occultation of Alcyone), the moon will present the first of a series of 49 monthly occultations of the star Elnath (Beta Tauri) from September 7, 2023, until April 11, 2027. Elnath, the second-brightest star in the constellation Taurus, is about half as bright as Aldebaran, Taurus’ one and only 1st-magnitude star.
Aldebaran marks the tip of a V-shaped pattern of stars – really, a star cluster – called the Hyades, representing the Bull’s face. Yet Aldebaran isn’t part of this star cluster. It’s a chance alignment, with the Hyades cluster at more than twice Aldebaran’s distance away. You’ll have an easier time seeing the V-shaped face of the Bull in the second half of he month, when the moon drops out of the evening sky.
By the way, the star Zeta Tauri is nearing the end of its present occultation series. The first of these 22 monthly occultations began on June 13, 2018, and the final occultation will take place on February 5, 2020. The next to the last occultation will happen on January 8, 2020. Yet, from virtually everywhere worldwide (except far northerly latitudes), the moon will swing just a touch north of this 3rd-magnitude star, which is a good 30 times fainter than Aldebaran.
Ruddy Aldebaran depicts the Bull’s fiery red eye, the star Elnath marks the tip of the northern horn and the star Zeta Tauri pinpoints the tip of the southern horn. After the moon and Aldebaran first pop into view at nightfall, they’ll continue (along with the other stars) to move westward as Earth spins under the sky. These two luminaries will set in the west in the wee hours after midnight.
Want to know when the moon sets in your part of the world? Visit Sunrise Sunset Calendars and remember to check the moonrise and moonset box.
Want to know in which constellation of the zodiac the moon resides? Visit Heavens-Above.
When the moon is no longer around to guide you, use Orion’s Belt to find Aldebaran. 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 whereas the Pleiades star cluster hovers to the north of the ecliptic.
The moon and Aldebaran go westward across the sky tonight for the same reason that the sun goes westward during the day. The Earth rotates from west to east on its rotational axis. So, each day, as the Earth spins full circle beneath the heavens, the sun, moon, stars and planets all appear to go across the sky from east to west daily.
At the same time, the moon is actually traveling eastward in front of the constellation Taurus the Bull at the rate of about 1/2 degree (the moon’s angular diameter) per hour. Relative to the backdrop stars of the zodiac, the moon travels on the average of about 13 degrees per day.
If you watch the moon over the next several nights, you’ll see the waxing gibbous moon farther east relative to the backdrop stars than on the previous night, as shown on the feature sky chart at top. As it moves, the moon is edging closer toward full moon, which will come on the night of January 10, 2020.
Bottom line: This evening – January 6, 2020 – the misty-looking Pleiades star cluster is found to the north of the moon, while Aldebaran, the constellation Taurus’ brightest star, shines to the east of the January 6th moon. Look for the moon to be much closer to Aldebaran on the evening of January 7, 2020.
from EarthSky https://ift.tt/37HMkki
These next three nights – January 6, 7 and 8, 2020 – the bright waxing gibbous moon shines in front of the constellation Taurus the Bull. However, it will be difficult to envision the starlit figure of the Bull on these moonlit nights. Despite the lunar glare, you might see this constellation’s two major signposts: the star Aldebaran and the Pleiades star cluster, otherwise known as the Seven Sisters.
Fred Espenak – Mr. Eclipse – posted this image at EarthSky Facebook. This image is a stack of 20 individual 5-minute exposures through a Takahashi Epsilon 180ED Hyperbolic Astrograph using a Canon 6D DSLR. Photo via MrEclipse.com.
During the moon’s trek through Taurus, the moon passes to the south of the Pleiades and then to the north of Aldebaran. In fact, each month for many years to come, the moon will pass to the south of the Pleiades and to the north of Aldebaran. Yet, month by month, the moon will travel farther north in front of Taurus, until it goes so far north that it stages a series of 79 lunar occultations of Alcyone (the Pleiades’ brightest star) from September 5, 2023, until July 7, 2029.
Once the moon drops out of the evening sky, you can use the three stars of Orion’s Belt to find the star Aldebaran and the Pleiades star cluster. Image via Janne/Flickr.
What’s more, starting on September 7, 2023 (only two days after the initial occultation of Alcyone), the moon will present the first of a series of 49 monthly occultations of the star Elnath (Beta Tauri) from September 7, 2023, until April 11, 2027. Elnath, the second-brightest star in the constellation Taurus, is about half as bright as Aldebaran, Taurus’ one and only 1st-magnitude star.
Aldebaran marks the tip of a V-shaped pattern of stars – really, a star cluster – called the Hyades, representing the Bull’s face. Yet Aldebaran isn’t part of this star cluster. It’s a chance alignment, with the Hyades cluster at more than twice Aldebaran’s distance away. You’ll have an easier time seeing the V-shaped face of the Bull in the second half of he month, when the moon drops out of the evening sky.
By the way, the star Zeta Tauri is nearing the end of its present occultation series. The first of these 22 monthly occultations began on June 13, 2018, and the final occultation will take place on February 5, 2020. The next to the last occultation will happen on January 8, 2020. Yet, from virtually everywhere worldwide (except far northerly latitudes), the moon will swing just a touch north of this 3rd-magnitude star, which is a good 30 times fainter than Aldebaran.
Ruddy Aldebaran depicts the Bull’s fiery red eye, the star Elnath marks the tip of the northern horn and the star Zeta Tauri pinpoints the tip of the southern horn. After the moon and Aldebaran first pop into view at nightfall, they’ll continue (along with the other stars) to move westward as Earth spins under the sky. These two luminaries will set in the west in the wee hours after midnight.
Want to know when the moon sets in your part of the world? Visit Sunrise Sunset Calendars and remember to check the moonrise and moonset box.
Want to know in which constellation of the zodiac the moon resides? Visit Heavens-Above.
When the moon is no longer around to guide you, use Orion’s Belt to find Aldebaran. 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 whereas the Pleiades star cluster hovers to the north of the ecliptic.
The moon and Aldebaran go westward across the sky tonight for the same reason that the sun goes westward during the day. The Earth rotates from west to east on its rotational axis. So, each day, as the Earth spins full circle beneath the heavens, the sun, moon, stars and planets all appear to go across the sky from east to west daily.
At the same time, the moon is actually traveling eastward in front of the constellation Taurus the Bull at the rate of about 1/2 degree (the moon’s angular diameter) per hour. Relative to the backdrop stars of the zodiac, the moon travels on the average of about 13 degrees per day.
If you watch the moon over the next several nights, you’ll see the waxing gibbous moon farther east relative to the backdrop stars than on the previous night, as shown on the feature sky chart at top. As it moves, the moon is edging closer toward full moon, which will come on the night of January 10, 2020.
Bottom line: This evening – January 6, 2020 – the misty-looking Pleiades star cluster is found to the north of the moon, while Aldebaran, the constellation Taurus’ brightest star, shines to the east of the January 6th moon. Look for the moon to be much closer to Aldebaran on the evening of January 7, 2020.
