Longest sunsets happen around the solstice

Above photo: June solstice sunset in the nation of Oman, on the Arabian Peninsula, from our friend Priya Kumar. Thank you, Priya!

Here’s a natural phenomenon you might never have imagined. That is, the sun actually takes more time to set around the time of a solstice.

It’s true. The longest sunsets (and sunrises) occur at or near the solstices. The shortest sunsets (and sunrises) occur at or near the equinoxes. This is true whether you live in the Northern or Southern Hemisphere.

And, by the way, when we say sunset here, we’re talking about the actual number of minutes it takes for the body of the sun to sink below the western horizon.

Adrian Strand captured this photo on a beach in northwest England.

When is the solstice? In 2020, the Northern Hemisphere’s summer solstice – and Southern Hemisphere’s winter solstice – will fall on June 20 at 21:44 UTC.

In the United States, that translates to June 20 at 5:44 p.m EDT, 4:44 p.m. CDT, 3:44 p.m. MDT, 2:44 p.m. PDT, 1:44 p.m. Alaska Daylight Time and 11:44 a.m. Hawaii-Aleutian Daylight Time. Translate to your time zone.

Equinoxes and solstices, via Geosync. The Earth’s axis points straight up and down, with north at the top. The solstices are on the left (December solstice at top, June solstice at bottom) and the equinoxes are to the right (March equinox at top. September equinox at bottom).

Why is the sunset longer around the solstice? As viewed from both the Northern and Southern Hemispheres, the sun rises and sets farthest north at the June solstice and farthest south at the December solstice.

Now consider that the farther the sun sets from due west along the horizon, the shallower the angle of the setting sun. That means a longer duration for sunset at the solstices.

Meanwhile, at an equinox, the sun rises due east and sets due west. That means – on the day of an equinox – the setting sun hits the horizon at its steepest possible angle.

The sunset duration varies by latitude, but let’s just consider one latitude, 40 degrees north, the latitude of Denver or Philadelphia in the United States, Sardinia in the Mediterranean, or Beijing in China. At that latitude, on the day of a solstice, the sun sets in about 3 1/4 minutes.

On the other hand, at 40 degrees north latitude, the equinox sun sets in roughly 2 3/4 minutes.

At more northerly temperate latitudes, the sunset duration is greater; and at latitudes closer to the equator, the sunset duration is less. Near the Arctic Circle (65 degrees north latitude), the duration of a solstice sunset lasts about 15 minutes. At the equator (0 degrees latitude), the solstice sun takes a little over 2 1/4 minutes to set.

Regardless of latitude, however, the duration of sunset is always longest at or near the solstices.

As it turns out, the sunset and sunrise are a tad longer on a December solstice than they are on a June solstice. That’s because the sun is closer to Earth in December than it is in June. Therefore, the sun’s disk looms a bit larger in our sky in December, and so it takes slightly longer to set.

Additionally, the closer December sun moves eastward upon the ecliptic at a faster clip, helping to slow down the December solstice sunset (and sunrise) even more. For instance, at 50 degrees north latitude, the winter solstice sunset (sunrise) lasts about 4 minutes and 18 seconds, or about 8 seconds longer than the sunset (sunrise) on the summer solstice.

Solstices and equinoxes take place in Earth’s orbit around the sun.

Bottom line: Here’s a natural phenomenon you might never have imagined. That is, the longest sunsets happen around the time of a solstice.

Help support EarthSky! Visit the EarthSky store for to see the great selection of educational tools and team gear we have to offer.

Help EarthSky keep going! Please donate what you can.

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Above photo: June solstice sunset in the nation of Oman, on the Arabian Peninsula, from our friend Priya Kumar. Thank you, Priya!

Here’s a natural phenomenon you might never have imagined. That is, the sun actually takes more time to set around the time of a solstice.

It’s true. The longest sunsets (and sunrises) occur at or near the solstices. The shortest sunsets (and sunrises) occur at or near the equinoxes. This is true whether you live in the Northern or Southern Hemisphere.

And, by the way, when we say sunset here, we’re talking about the actual number of minutes it takes for the body of the sun to sink below the western horizon.

Adrian Strand captured this photo on a beach in northwest England.

When is the solstice? In 2020, the Northern Hemisphere’s summer solstice – and Southern Hemisphere’s winter solstice – will fall on June 20 at 21:44 UTC.

In the United States, that translates to June 20 at 5:44 p.m EDT, 4:44 p.m. CDT, 3:44 p.m. MDT, 2:44 p.m. PDT, 1:44 p.m. Alaska Daylight Time and 11:44 a.m. Hawaii-Aleutian Daylight Time. Translate to your time zone.

Equinoxes and solstices, via Geosync. The Earth’s axis points straight up and down, with north at the top. The solstices are on the left (December solstice at top, June solstice at bottom) and the equinoxes are to the right (March equinox at top. September equinox at bottom).

Why is the sunset longer around the solstice? As viewed from both the Northern and Southern Hemispheres, the sun rises and sets farthest north at the June solstice and farthest south at the December solstice.

Now consider that the farther the sun sets from due west along the horizon, the shallower the angle of the setting sun. That means a longer duration for sunset at the solstices.

Meanwhile, at an equinox, the sun rises due east and sets due west. That means – on the day of an equinox – the setting sun hits the horizon at its steepest possible angle.

The sunset duration varies by latitude, but let’s just consider one latitude, 40 degrees north, the latitude of Denver or Philadelphia in the United States, Sardinia in the Mediterranean, or Beijing in China. At that latitude, on the day of a solstice, the sun sets in about 3 1/4 minutes.

On the other hand, at 40 degrees north latitude, the equinox sun sets in roughly 2 3/4 minutes.

At more northerly temperate latitudes, the sunset duration is greater; and at latitudes closer to the equator, the sunset duration is less. Near the Arctic Circle (65 degrees north latitude), the duration of a solstice sunset lasts about 15 minutes. At the equator (0 degrees latitude), the solstice sun takes a little over 2 1/4 minutes to set.

Regardless of latitude, however, the duration of sunset is always longest at or near the solstices.

As it turns out, the sunset and sunrise are a tad longer on a December solstice than they are on a June solstice. That’s because the sun is closer to Earth in December than it is in June. Therefore, the sun’s disk looms a bit larger in our sky in December, and so it takes slightly longer to set.

Additionally, the closer December sun moves eastward upon the ecliptic at a faster clip, helping to slow down the December solstice sunset (and sunrise) even more. For instance, at 50 degrees north latitude, the winter solstice sunset (sunrise) lasts about 4 minutes and 18 seconds, or about 8 seconds longer than the sunset (sunrise) on the summer solstice.

Solstices and equinoxes take place in Earth’s orbit around the sun.

Bottom line: Here’s a natural phenomenon you might never have imagined. That is, the longest sunsets happen around the time of a solstice.

Help support EarthSky! Visit the EarthSky store for to see the great selection of educational tools and team gear we have to offer.

Help EarthSky keep going! Please donate what you can.

from EarthSky https://ift.tt/2YjP4mt

Covid-19 spreads through the air. That’s a big challenge for reopening

Coughing, sneezing, talking and even just breathing can produce airborne particles that can spread SARS-CoV-2. Image via Stanislaw Pytel/ Digital Vision/ Getty Images.

Douglas Reed, University of Pittsburgh

I am a scientist that studies infectious diseases and I specialize in severe respiratory infections, but I also serve as a member of my church’s safety team.

Over the past few weeks as states began to loosen restrictions, we have been discussing if and how to safely start services again. But the coronavirus is far from gone. As we try and figure out how to hold services while protecting our members, one question is of particular concern: How common is airborne spread of the virus?

How to spread a virus

Respiratory infections are generally spread in three possible ways: from direct contact, from droplets and from airborne particles.

Contact transmission occurs when a person touches an object that has live virus on it – called a fomite – and gets sick.

Droplets are small particles of mucus or saliva that come from a person’s mouth or nose when they cough or talk. They range in size from 5 microns to hundreds of microns in diameter – a red blood cell to a grain of sand. Most droplets, particularly large ones, fall to the ground within seconds and don’t usually travel more than 3 or 6 feet (1 or 2 meters). If a person coughed on you and you got sick, that would be droplet transmission.

Airborne transmission happens because of airborne particles known as droplet nuclei. Droplet nuclei are any bit of mucus or saliva smaller than 5 microns across. People produce droplet nuclei when they talk, but they can also be formed when small droplets evaporate and shrink in size. Many of these droplets shrink so much that they begin to float before they hit the ground, thus becoming aerosols.

People produce thousands of these droplet nuclei per second while talking and the aerosolized particles can contain live viruses and float in the air for hours. They are easy to inhale, and if they contain live virus, can get people sick. The ability of droplet nuclei to transmit the coronavirus has a massive impact on if and how places like my church can reopen.

Droplet nuclei and other aerosols can float around for hours in the air, and if inhaled, spread the coronavirus. Image via Jorg Greuel/ Photodisc/ Getty Images.

Early on in the pandemic, experts at the Centers for Disease Control and Prevention and the World Health Organization were most concerned about the coronavirus being transmitted from surfaces and from large droplets.

But the more research is done on SARS-CoV-2, the more evidence there is that airborne transmission is occurring although it is controversial. Both the CDC and WHO are now recommending that the general population wear masks, but for people going about their lives and wondering how to reopen public areas across the world, the question remains: Just how important is airborne transmission?

Airborne longevity in the lab

To get infected, a person needs to come in contact with live virus. If the virus dies before a person can inhale it, they won’t get sick.

To test how well SARS-CoV-2 can live in the air, researchers use special equipment to create aerosolized virus and keep it airborne for long periods of time. Researchers can then take samples of the virus and see how long it stays alive in an aerosol. An early study from researchers at the National Institute of Health kept the virus airborne for four hours and found live virus the whole time. A subsequent pre-print study that I was part of found that the coronavirus can stay alive for up to 16 hours in the air.

Neither the initial study nor the one that I was involved with measured the impact of temperature, humidity, ultraviolet light or pollution on survival of the virus in aerosols. There is evidence that simulated sunlight can inactivate 90% of SARS-CoV-2 viruses in saliva on surfaces or in aerosols within seven minutes. These studies suggest that the virus would be rapidly inactivated outdoors, but the risk of transmission indoors would remain.

A choir practice in Washington State was the site of a huge outbreak and offers one of the strongest pieces of evidence for airborne transmission. Image via Satoshi-K/E+/ Getty Images.

Evidence from the real world

Laboratory studies can provide valuable insight, but real world scenarios point to the true risk from airborne transmission.

Reports from China, Singapore and Nebraska have found the virus in patient rooms and at very low levels in the ventilation system of hospitals where COVID-19 patients were treated. The report from China also found evidence of the virus at the entrance of a department store. So far, this sampling has been done using polymerase chain reaction tests which look for pieces of viral DNA, not live virus. They can’t tell researchers if what they are finding is infectious.

For direct evidence of the risks of airborne transmission, we can look to a few case studies in the U.S. and abroad.

One study tracked how a single infected person at a call center in South Korea infected 94 other people. There is also the widely reported of case of one infected person at a restaurant in Guangzhou, China, spreading the virus to nine other people because of the airflow created by an air conditioning unit in the room.

Perhaps most striking, especially for myself as we contemplate how to reopen our church, is the example of the church choir in Skagit County, Washington. A single individual singing at a choir practice infected 52 other people. Singing and loud vocalization in general can produce a lot of aerosols, and evidence shows that some people are super-emitters of aerosols even during normal speech. It’s likely that some infections in this incident occurred from droplets or direct contact, but
the fact that one person was able to infect so many people strongly suggests that airborne transmission was the driving factor in this outbreak.

A paper published just last week compared the success of mitigation measures – like social distancing or mask wearing – to try and determine how the virus is spreading. The authors concluded that aerosol transmission was the dominant route. This conclusion is hotly debated in the scientific community, but this study and others do show the effectiveness of masks in slowing the spread of COVID-19.

Masks, in addition to social distancing, are the best tool available to reduce airborne spread and are necessary as churches and other public places open up. Image via AP Photo/ Damian Dovarganes.

What does this mean for reopening and for individuals?

The evidence strongly suggests that airborne transmission happens easily and is likely a significant driver of this pandemic. It must be taken seriously as people begin to venture back out into the world.

Thankfully, there is an easy, if not perfect way you can reduce airborne transmission: masks. Since people can spread the virus when they are pre-symptomatic or asymptomatic, universal mask wearing is a very effective, low-cost way to slow down the pandemic.

Since the primary risk is indoors, increasing ventilation rates and not recirculating air inside buildings would remove the virus from the indoor environment faster.

My church has decided to reopen, but we are only planning to allow limited numbers of people in the church and spreading them throughout the sanctuary to maintain social distancing. And at least for now, everyone is required to wear masks. Especially while singing.

Douglas Reed, Associate Professor of Immunology, University of Pittsburgh

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bottom line: How the Covid-19 spreads, including how people are getting sick from coronavirus spreading through the air, which is a big challenge for reopening.

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

Coughing, sneezing, talking and even just breathing can produce airborne particles that can spread SARS-CoV-2. Image via Stanislaw Pytel/ Digital Vision/ Getty Images.

Douglas Reed, University of Pittsburgh

I am a scientist that studies infectious diseases and I specialize in severe respiratory infections, but I also serve as a member of my church’s safety team.

Over the past few weeks as states began to loosen restrictions, we have been discussing if and how to safely start services again. But the coronavirus is far from gone. As we try and figure out how to hold services while protecting our members, one question is of particular concern: How common is airborne spread of the virus?

How to spread a virus

Respiratory infections are generally spread in three possible ways: from direct contact, from droplets and from airborne particles.

Contact transmission occurs when a person touches an object that has live virus on it – called a fomite – and gets sick.

Droplets are small particles of mucus or saliva that come from a person’s mouth or nose when they cough or talk. They range in size from 5 microns to hundreds of microns in diameter – a red blood cell to a grain of sand. Most droplets, particularly large ones, fall to the ground within seconds and don’t usually travel more than 3 or 6 feet (1 or 2 meters). If a person coughed on you and you got sick, that would be droplet transmission.

Airborne transmission happens because of airborne particles known as droplet nuclei. Droplet nuclei are any bit of mucus or saliva smaller than 5 microns across. People produce droplet nuclei when they talk, but they can also be formed when small droplets evaporate and shrink in size. Many of these droplets shrink so much that they begin to float before they hit the ground, thus becoming aerosols.

People produce thousands of these droplet nuclei per second while talking and the aerosolized particles can contain live viruses and float in the air for hours. They are easy to inhale, and if they contain live virus, can get people sick. The ability of droplet nuclei to transmit the coronavirus has a massive impact on if and how places like my church can reopen.

Droplet nuclei and other aerosols can float around for hours in the air, and if inhaled, spread the coronavirus. Image via Jorg Greuel/ Photodisc/ Getty Images.

Early on in the pandemic, experts at the Centers for Disease Control and Prevention and the World Health Organization were most concerned about the coronavirus being transmitted from surfaces and from large droplets.

But the more research is done on SARS-CoV-2, the more evidence there is that airborne transmission is occurring although it is controversial. Both the CDC and WHO are now recommending that the general population wear masks, but for people going about their lives and wondering how to reopen public areas across the world, the question remains: Just how important is airborne transmission?

Airborne longevity in the lab

To get infected, a person needs to come in contact with live virus. If the virus dies before a person can inhale it, they won’t get sick.

To test how well SARS-CoV-2 can live in the air, researchers use special equipment to create aerosolized virus and keep it airborne for long periods of time. Researchers can then take samples of the virus and see how long it stays alive in an aerosol. An early study from researchers at the National Institute of Health kept the virus airborne for four hours and found live virus the whole time. A subsequent pre-print study that I was part of found that the coronavirus can stay alive for up to 16 hours in the air.

Neither the initial study nor the one that I was involved with measured the impact of temperature, humidity, ultraviolet light or pollution on survival of the virus in aerosols. There is evidence that simulated sunlight can inactivate 90% of SARS-CoV-2 viruses in saliva on surfaces or in aerosols within seven minutes. These studies suggest that the virus would be rapidly inactivated outdoors, but the risk of transmission indoors would remain.

A choir practice in Washington State was the site of a huge outbreak and offers one of the strongest pieces of evidence for airborne transmission. Image via Satoshi-K/E+/ Getty Images.

Evidence from the real world

Laboratory studies can provide valuable insight, but real world scenarios point to the true risk from airborne transmission.

Reports from China, Singapore and Nebraska have found the virus in patient rooms and at very low levels in the ventilation system of hospitals where COVID-19 patients were treated. The report from China also found evidence of the virus at the entrance of a department store. So far, this sampling has been done using polymerase chain reaction tests which look for pieces of viral DNA, not live virus. They can’t tell researchers if what they are finding is infectious.

For direct evidence of the risks of airborne transmission, we can look to a few case studies in the U.S. and abroad.

One study tracked how a single infected person at a call center in South Korea infected 94 other people. There is also the widely reported of case of one infected person at a restaurant in Guangzhou, China, spreading the virus to nine other people because of the airflow created by an air conditioning unit in the room.

Perhaps most striking, especially for myself as we contemplate how to reopen our church, is the example of the church choir in Skagit County, Washington. A single individual singing at a choir practice infected 52 other people. Singing and loud vocalization in general can produce a lot of aerosols, and evidence shows that some people are super-emitters of aerosols even during normal speech. It’s likely that some infections in this incident occurred from droplets or direct contact, but
the fact that one person was able to infect so many people strongly suggests that airborne transmission was the driving factor in this outbreak.

A paper published just last week compared the success of mitigation measures – like social distancing or mask wearing – to try and determine how the virus is spreading. The authors concluded that aerosol transmission was the dominant route. This conclusion is hotly debated in the scientific community, but this study and others do show the effectiveness of masks in slowing the spread of COVID-19.

Masks, in addition to social distancing, are the best tool available to reduce airborne spread and are necessary as churches and other public places open up. Image via AP Photo/ Damian Dovarganes.

What does this mean for reopening and for individuals?

The evidence strongly suggests that airborne transmission happens easily and is likely a significant driver of this pandemic. It must be taken seriously as people begin to venture back out into the world.

Thankfully, there is an easy, if not perfect way you can reduce airborne transmission: masks. Since people can spread the virus when they are pre-symptomatic or asymptomatic, universal mask wearing is a very effective, low-cost way to slow down the pandemic.

Since the primary risk is indoors, increasing ventilation rates and not recirculating air inside buildings would remove the virus from the indoor environment faster.

My church has decided to reopen, but we are only planning to allow limited numbers of people in the church and spreading them throughout the sanctuary to maintain social distancing. And at least for now, everyone is required to wear masks. Especially while singing.

Douglas Reed, Associate Professor of Immunology, University of Pittsburgh

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Bottom line: How the Covid-19 spreads, including how people are getting sick from coronavirus spreading through the air, which is a big challenge for reopening.

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

Summer solstice tale of 2 cities

Sunset over Manhattan, June 5, 2016, by Jennifer Khordi. Visit Khordi Photography on Facebook.

Around the time of the June solstice, the sun sets at virtually the same time in both New York City, New York, and St. Augustine, Florida. On June 20, 2020, the sun sets around 8:30 p.m. Eastern Daylight Time (EDT) in both places.

What’s going on here? Doesn’t the sun set later farther north at this time of year? What about the phenomenon of midnight twilight and midnight sun, after all? It’s true that – for places farther north in summer – the sun stays out longer. But St. Augustine lodges about 7.5 degrees of longitude to the west of New York City. Our planet takes about 30 minutes to rotate this 7.5 degrees.

Therefore, on any day of the year, the sun reaches its noontime position some 30 minutes later in St. Augustine than it does in New York City. For instance, on June 20, 2020, the noonday sun reaches its high point for the day at 12:57 p.m. EDT in New York City – yet in St. Augustine, solar noon comes about 30 minutes later, at 1:27 p.m. EDT.

Because New York is appreciably north of St. Augustine, New York’s afternoon daylight (from solar noon to sunset) lasts some 30 minutes longer on the day of the June solstice than it does in St. Augustine.

Thus, the longer period of daylight in New York cancels out the later noontime appearance of the sun in St. Augustine, to give both localities the same sunset time on the day of the June solstice. The table below helps to clarify.

Sunrise/solar noon/sunset times on June 20, 2020

City	Sunrise	Solar Noon	Sunset
New York	5:24 a.m.	12:57 p.m.	8:30 p.m.
St. Augustine	6:24 a.m.	1:27 p.m.	8:29 p.m.

NYC and St. Augustine both use Eastern time. But the noonday sun comes 30 minutes later to St. Augustine because it resides 7.5 degrees of longitude west of New York City.

In other words, from sunrise to sunset on the June solstice, New York City has about an hour more daylight than St. Augustine does. (That’s 30 minutes more morning daylight and 30 minutes more afternoon daylight.) Although the sunset occurs at virtually the same time for both cities, the sunrise happens an hour earlier in New York City. Look again at the sunrise/solar noon/sunset table above.

Earth’s terminator – line of sunset – nearly parallels the Eastern Seaboard on the day of the June solstice.

The image above is a simulated view of Earth as the sun is setting around the time of the June summer solstice. Note that the terminator pretty much aligns with the U. S. East Coast, providing a similar sunset time for coastal dwellers.

Enter the equinoxes

Some three – and nine – months after the June solstice, St. Augustine and New York City receive the same amount of daylight on the days of the September and March equinoxes. On the equinoxes, noontime as well as sunrise and sunset come 30 minutes later in St. Augustine than they do in New York City. The simulated view of Earth below shows the terminator – the sunrise line – running due north and south on the equinox. Neither the sunrise terminator nor sunset terminator comes anywhere close to aligning with the U.S. East Coast at either equinox.

Sunrise/solar noon/sunset times on September 22, 2020

City	Sunrise	Solar Noon	Sunset
New York	6:42 a.m.	12:49 p.m.	6:55 p.m.
St. Augustine	7:12 a.m.	1:18 p.m.	7:23 p.m.

The terminator – sunrise line – runs due north and south on the equinoxes. The sunset line, though not shown, also runs north and south. Image via Earth and Moon Viewer.

Sunrise/solar noon/sunset times on March 20, 2021

City	Sunrise	Solar Noon	Sunset
New York	6:58 a.m.	1:03 p.m.	7:08 p.m.
St. Augustine	7:28 a.m.	1:32 p.m.	7:36 p.m.

Enter the December solstice

Six months after the June solstice, it’s the December winter solstice for the Northern Hemisphere, coming yearly on or near December 21. Now, the situation is reversed from the June solstice, with St. Augustine receiving an hour more daylight than New York City.

Because St. Augustine lies appreciably south of New York City, St. Augustine’s morning daylight (from sunrise to solar noon) lasts 30 minutes longer than in New York City on the day of the December winter solstice. Thus, the more daylight in St. Augustine cancels out the earlier noontime in New York City, to give both localities the same sunrise time on the December solstice. (See sunrise/solar noon/sunset table below.)

Simulation of the line of sunrise as it hits the U.S. eastern seaboard around the December solstice. Image via U.S. Naval Observatory.

Look above at the simulated view of Earth as the sun is rising over the Eastern Seaboard of the United States on the day of the winter solstice. Note that the terminator – the sunrise line – pretty much coincides with the East Coast, giving a similar sunrise time for residents along the Atlantic Seaboard.

Sunrise/solar noon/sunset times on December 21, 2020

City	Sunrise	Solar Noon	Sunset
New York	7:16 a.m.	11:54 a.m.	4:32 p.m.
St. Augustine	7:16 a.m.	12:24 p.m.	5:30 p.m.

From sunrise to sunset on the day of the winter solstice, St. Augustine residents enjoy about an hour more daylight than those in New York City. Although the sunrise occurs at about the same time for both cities, the sunset happens an hour later in St. Augustine on the day of the winter solstice.

Bottom Line: On the day of the June summer solstice, the sun sets at the same time in both St. Augustine, Florida, and New York City, New York. However, New York City enjoys an hour more daylight. Six months later, on the day of the December solstice, it’s the exact opposite. It’s the sunrise that happens at the same time in both places, yet it’s then St. Augustine’s turn to enjoy an extra hour of sunshine.

Help EarthSky keep going! Please donate what you can.

from EarthSky https://ift.tt/319eAg3

Sunset over Manhattan, June 5, 2016, by Jennifer Khordi. Visit Khordi Photography on Facebook.

Around the time of the June solstice, the sun sets at virtually the same time in both New York City, New York, and St. Augustine, Florida. On June 20, 2020, the sun sets around 8:30 p.m. Eastern Daylight Time (EDT) in both places.

What’s going on here? Doesn’t the sun set later farther north at this time of year? What about the phenomenon of midnight twilight and midnight sun, after all? It’s true that – for places farther north in summer – the sun stays out longer. But St. Augustine lodges about 7.5 degrees of longitude to the west of New York City. Our planet takes about 30 minutes to rotate this 7.5 degrees.

Therefore, on any day of the year, the sun reaches its noontime position some 30 minutes later in St. Augustine than it does in New York City. For instance, on June 20, 2020, the noonday sun reaches its high point for the day at 12:57 p.m. EDT in New York City – yet in St. Augustine, solar noon comes about 30 minutes later, at 1:27 p.m. EDT.

Because New York is appreciably north of St. Augustine, New York’s afternoon daylight (from solar noon to sunset) lasts some 30 minutes longer on the day of the June solstice than it does in St. Augustine.

Thus, the longer period of daylight in New York cancels out the later noontime appearance of the sun in St. Augustine, to give both localities the same sunset time on the day of the June solstice. The table below helps to clarify.

Sunrise/solar noon/sunset times on June 20, 2020

City	Sunrise	Solar Noon	Sunset
New York	5:24 a.m.	12:57 p.m.	8:30 p.m.
St. Augustine	6:24 a.m.	1:27 p.m.	8:29 p.m.

NYC and St. Augustine both use Eastern time. But the noonday sun comes 30 minutes later to St. Augustine because it resides 7.5 degrees of longitude west of New York City.

In other words, from sunrise to sunset on the June solstice, New York City has about an hour more daylight than St. Augustine does. (That’s 30 minutes more morning daylight and 30 minutes more afternoon daylight.) Although the sunset occurs at virtually the same time for both cities, the sunrise happens an hour earlier in New York City. Look again at the sunrise/solar noon/sunset table above.

Earth’s terminator – line of sunset – nearly parallels the Eastern Seaboard on the day of the June solstice.

The image above is a simulated view of Earth as the sun is setting around the time of the June summer solstice. Note that the terminator pretty much aligns with the U. S. East Coast, providing a similar sunset time for coastal dwellers.

Enter the equinoxes

Some three – and nine – months after the June solstice, St. Augustine and New York City receive the same amount of daylight on the days of the September and March equinoxes. On the equinoxes, noontime as well as sunrise and sunset come 30 minutes later in St. Augustine than they do in New York City. The simulated view of Earth below shows the terminator – the sunrise line – running due north and south on the equinox. Neither the sunrise terminator nor sunset terminator comes anywhere close to aligning with the U.S. East Coast at either equinox.

Sunrise/solar noon/sunset times on September 22, 2020

City	Sunrise	Solar Noon	Sunset
New York	6:42 a.m.	12:49 p.m.	6:55 p.m.
St. Augustine	7:12 a.m.	1:18 p.m.	7:23 p.m.

The terminator – sunrise line – runs due north and south on the equinoxes. The sunset line, though not shown, also runs north and south. Image via Earth and Moon Viewer.

Sunrise/solar noon/sunset times on March 20, 2021

City	Sunrise	Solar Noon	Sunset
New York	6:58 a.m.	1:03 p.m.	7:08 p.m.
St. Augustine	7:28 a.m.	1:32 p.m.	7:36 p.m.

Enter the December solstice

Six months after the June solstice, it’s the December winter solstice for the Northern Hemisphere, coming yearly on or near December 21. Now, the situation is reversed from the June solstice, with St. Augustine receiving an hour more daylight than New York City.

Because St. Augustine lies appreciably south of New York City, St. Augustine’s morning daylight (from sunrise to solar noon) lasts 30 minutes longer than in New York City on the day of the December winter solstice. Thus, the more daylight in St. Augustine cancels out the earlier noontime in New York City, to give both localities the same sunrise time on the December solstice. (See sunrise/solar noon/sunset table below.)

Simulation of the line of sunrise as it hits the U.S. eastern seaboard around the December solstice. Image via U.S. Naval Observatory.

Look above at the simulated view of Earth as the sun is rising over the Eastern Seaboard of the United States on the day of the winter solstice. Note that the terminator – the sunrise line – pretty much coincides with the East Coast, giving a similar sunrise time for residents along the Atlantic Seaboard.

Sunrise/solar noon/sunset times on December 21, 2020

City	Sunrise	Solar Noon	Sunset
New York	7:16 a.m.	11:54 a.m.	4:32 p.m.
St. Augustine	7:16 a.m.	12:24 p.m.	5:30 p.m.

From sunrise to sunset on the day of the winter solstice, St. Augustine residents enjoy about an hour more daylight than those in New York City. Although the sunrise occurs at about the same time for both cities, the sunset happens an hour later in St. Augustine on the day of the winter solstice.

Bottom Line: On the day of the June summer solstice, the sun sets at the same time in both St. Augustine, Florida, and New York City, New York. However, New York City enjoys an hour more daylight. Six months later, on the day of the December solstice, it’s the exact opposite. It’s the sunrise that happens at the same time in both places, yet it’s then St. Augustine’s turn to enjoy an extra hour of sunshine.

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Celebrate solstice sunrise at Stonehenge live online

View of the Heel Stone at summer solstice sunrise, as seen from inside the Stonehenge monument. Image via mysticrealms.org.

Wherever you are in the world, you can celebrate the 2020 June solstice by watching the sun rise at Stonehenge.

Every year, thousands of visitors gather at the neolithic Stonehenge monument in Wiltshire, England, to celebrate the first sunrise of the Northern Hemisphere summer. However, this year’s event has been canceled; Stonehenge is currently closed due to Covid-19. While this news is disappointing, there’s good news: For the first time, English Heritage – which has provided access to the event since 2000 – will instead stream the solstice event online.

The event starts at sunset on Saturday (20:26 UTC on June 20) and goes through sunrise on Sunday (03:53 UTC on June 21). Translate UTC to your time. Here is the official Facebook event page, where you’ll be able to watch the livestream. You can also access the event via Stonehenge on Twitter.

Experience the solstice at Stonehenge – live online – beginning at sunset on Saturday (20:26 UTC on June 20) and lasting through sunrise on Sunday (03:52 UTC on June 21). Translate UTC to your time.

For everyone's safety and wellbeing, we've had to cancel this year's summer solstice celebrations at Stonehenge.

We know how special this occasion is to so many of you, and we'll be live streaming it for free online. pic.twitter.com/zMi0NzCmbO

— English Heritage (@EnglishHeritage) May 12, 2020

Stonehenge director Nichola Tasker told The Salisbury Journal:

We hope that our live stream offers an alternative opportunity for people near and far to connect with this spiritual place at such a special time of year and we look forward to welcoming everyone back next year.

We know how strong the draw to come is for some people, but I would take this opportunity to say please do not travel to Stonehenge this summer solstice, but watch it online instead.

Stonehenge has been closed since March 18, 2020, as the British government introduced measures to combat the coronavirus pandemic. Image via The Salisbury Journal

Stonehenge, in England, was built in three phases between about 3,000 B.C. and 1,600 B.C., and its purpose remains under study. However, it’s known that if you stand in just the right place inside the Stonehenge monument on the day of the northern summer solstice, facing northeast through the entrance towards a rough-hewn stone outside the circle – known as the Heel Stone – you will see the sun rise above the Heel Stone, as illustrated in the image at the top.

Here’s a video tour of Stonehenge from English Heritage on Facebook:

The BBC reported that about 12,000 people attended the neolithic site in Wiltshire to watch the sun rise at on June 20, 2016. Image via BBC.

In the Northern Hemisphere at this time of year, the sun is shining on us most directly at midday. Except at high northerly latitudes, above the Arctic Circle – where daylight is continuous for many months – the day on which the summer solstice occurs is the day of the year with the longest period of daylight. Meanwhile, it is the shortest day for Earth’s Southern Hemisphere.

At the northern summer solstice – always around June 20 – the sun’s path stops moving northward in the sky. For us in the Northern Hemisphere, it’s the day on which the days stop growing longer and will soon begin to shorten again. For this reason, the summer solstice is a time of festivals and celebrations around this hemisphere of Earth.

Summer solstice at Stonehenge via stonehengetrips.com.

The Stonehenge Free Festival was a British free festival from 1974 to 1984 held at Stonehenge during the month of June, and culminating on the summer solstice. The festival was a celebration of various alternative cultures. The Tibetan Ukrainian Mountain Troupe, The Tepee People, Circus Normal, the Peace Convoy, New Age Travellers and the Wallys were notable counterculture attendees. Image via Wikipedia.

Stonehenge is tied to the winter solstice, too. At Stonehenge on the day of the northern winter solstice (always around December 20), people watch as the sun sets in the midst of three great stones – known as the Trilithon – consisting of two large vertical stones supporting a third, horizontal stone across the top.

In the case of Stonehenge, this great Trilithon faces outwards from the center of the monument, with its smooth flat face turned toward the midwinter sun. In fact, the primary axis of Stonehenge seems to have been carefully aligned on a sight-line pointing to the winter solstice sunset.

EarthSky Facebook friend Buddy Puckhaber of South Carolina took this photo of Stonehenge in the early morning, while visiting. He said, “My wife and I were among the first visitors of the day.” Thank you, Buddy!

This huge megalithic monument shows how carefully our ancestors watched the sun. Astronomical observations such as these surely controlled human activities such as the mating of animals, the sowing of crops and the metering of winter reserves between harvests. Stonehenge is perhaps the most famous of of the ancient astronomical monuments found around the world.

When Stonehenge was first opened to the public it was possible to walk among the stones – even climb on them.

The stones were roped off in 1977 as a result of serious erosion. Today, visitors to the monument are not permitted to touch the stones, but, if you go, you will be able to walk around the monument from a short distance away. Visitors can also make special bookings to access the stones throughout the year.

Another beautiful shot of Stonehenge from our friend Buddy Puckhaber. Thank you, Buddy.

Enjoying EarthSky? Sign up for our free daily newsletter today!

Bottom line: How to celebrate the 2020 June solstice sunrise at Stonehenge live online.

from EarthSky https://ift.tt/3fBO0Qx

View of the Heel Stone at summer solstice sunrise, as seen from inside the Stonehenge monument. Image via mysticrealms.org.

Wherever you are in the world, you can celebrate the 2020 June solstice by watching the sun rise at Stonehenge.

Every year, thousands of visitors gather at the neolithic Stonehenge monument in Wiltshire, England, to celebrate the first sunrise of the Northern Hemisphere summer. However, this year’s event has been canceled; Stonehenge is currently closed due to Covid-19. While this news is disappointing, there’s good news: For the first time, English Heritage – which has provided access to the event since 2000 – will instead stream the solstice event online.

The event starts at sunset on Saturday (20:26 UTC on June 20) and goes through sunrise on Sunday (03:53 UTC on June 21). Translate UTC to your time. Here is the official Facebook event page, where you’ll be able to watch the livestream. You can also access the event via Stonehenge on Twitter.

Experience the solstice at Stonehenge – live online – beginning at sunset on Saturday (20:26 UTC on June 20) and lasting through sunrise on Sunday (03:52 UTC on June 21). Translate UTC to your time.

For everyone's safety and wellbeing, we've had to cancel this year's summer solstice celebrations at Stonehenge.

We know how special this occasion is to so many of you, and we'll be live streaming it for free online. pic.twitter.com/zMi0NzCmbO

— English Heritage (@EnglishHeritage) May 12, 2020

Stonehenge director Nichola Tasker told The Salisbury Journal:

We hope that our live stream offers an alternative opportunity for people near and far to connect with this spiritual place at such a special time of year and we look forward to welcoming everyone back next year.

We know how strong the draw to come is for some people, but I would take this opportunity to say please do not travel to Stonehenge this summer solstice, but watch it online instead.

Stonehenge has been closed since March 18, 2020, as the British government introduced measures to combat the coronavirus pandemic. Image via The Salisbury Journal

Stonehenge, in England, was built in three phases between about 3,000 B.C. and 1,600 B.C., and its purpose remains under study. However, it’s known that if you stand in just the right place inside the Stonehenge monument on the day of the northern summer solstice, facing northeast through the entrance towards a rough-hewn stone outside the circle – known as the Heel Stone – you will see the sun rise above the Heel Stone, as illustrated in the image at the top.

Here’s a video tour of Stonehenge from English Heritage on Facebook:

The BBC reported that about 12,000 people attended the neolithic site in Wiltshire to watch the sun rise at on June 20, 2016. Image via BBC.

In the Northern Hemisphere at this time of year, the sun is shining on us most directly at midday. Except at high northerly latitudes, above the Arctic Circle – where daylight is continuous for many months – the day on which the summer solstice occurs is the day of the year with the longest period of daylight. Meanwhile, it is the shortest day for Earth’s Southern Hemisphere.

At the northern summer solstice – always around June 20 – the sun’s path stops moving northward in the sky. For us in the Northern Hemisphere, it’s the day on which the days stop growing longer and will soon begin to shorten again. For this reason, the summer solstice is a time of festivals and celebrations around this hemisphere of Earth.

Summer solstice at Stonehenge via stonehengetrips.com.

The Stonehenge Free Festival was a British free festival from 1974 to 1984 held at Stonehenge during the month of June, and culminating on the summer solstice. The festival was a celebration of various alternative cultures. The Tibetan Ukrainian Mountain Troupe, The Tepee People, Circus Normal, the Peace Convoy, New Age Travellers and the Wallys were notable counterculture attendees. Image via Wikipedia.

Stonehenge is tied to the winter solstice, too. At Stonehenge on the day of the northern winter solstice (always around December 20), people watch as the sun sets in the midst of three great stones – known as the Trilithon – consisting of two large vertical stones supporting a third, horizontal stone across the top.

In the case of Stonehenge, this great Trilithon faces outwards from the center of the monument, with its smooth flat face turned toward the midwinter sun. In fact, the primary axis of Stonehenge seems to have been carefully aligned on a sight-line pointing to the winter solstice sunset.

EarthSky Facebook friend Buddy Puckhaber of South Carolina took this photo of Stonehenge in the early morning, while visiting. He said, “My wife and I were among the first visitors of the day.” Thank you, Buddy!

This huge megalithic monument shows how carefully our ancestors watched the sun. Astronomical observations such as these surely controlled human activities such as the mating of animals, the sowing of crops and the metering of winter reserves between harvests. Stonehenge is perhaps the most famous of of the ancient astronomical monuments found around the world.

When Stonehenge was first opened to the public it was possible to walk among the stones – even climb on them.

The stones were roped off in 1977 as a result of serious erosion. Today, visitors to the monument are not permitted to touch the stones, but, if you go, you will be able to walk around the monument from a short distance away. Visitors can also make special bookings to access the stones throughout the year.

Another beautiful shot of Stonehenge from our friend Buddy Puckhaber. Thank you, Buddy.

Enjoying EarthSky? Sign up for our free daily newsletter today!

Bottom line: How to celebrate the 2020 June solstice sunrise at Stonehenge live online.

from EarthSky https://ift.tt/3fBO0Qx

SOHO’s 4,000th comet

The NASA/ESA Solar and Heliospheric Observatory – affectionately called SOHO – is easily history’s greatest comet discoverer. This space observatory is designed to study the sun, but it now also has 4,000 comets to its credit, with the 4,000th discovered this week. SOHO’s abundance of comet discoveries is in part thanks to the dedication of citizen scientists, who pore through its data, seeking the moving fuzzballs near the sun that turn out to be sun-grazing comets. Amateur astronomer and geophysics graduate Trygve Prestgard – originally from Norway, now in Grenoble, France – spotted the 4,000th comet in the SOHO data on June 15, 2020. NASA reported:

The comet is nicknamed SOHO-4000, pending an official designation from the Minor Planet Center.

The 3,999th and 4,000th comets discovered by the SOHO spacecraft as they sped toward the sun. The spacecraft’s coronagraph, LASCO, uses a metal disk to block out the sun itself. This obscuring disk helps the instrument focus on the sun’s outer atmosphere or corona, and it allows SOHO to find comets! Image via ESA/ NASA/ SOHO/ Karl Battams.

Like most other SOHO-discovered comets, SOHO-4000 is part of the Kreutz family of sungrazers. The Kreutz family of comets all follow the same general trajectory, one that carries them skimming through the outer atmosphere of the sun. SOHO-4000 is on the small side, with a diameter in the range of 15-30 feet [4.5 to 9 meters], and it was extremely faint and close to the sun when discovered – meaning SOHO is the only observatory that has spotted the comet, as it’s impossible to see from Earth with or without a telescope.

Trygve Prestgard said:

I feel very fortunate to have found SOHO’s 4,000th comet. Although I knew that SOHO was nearing its 4,000th comet discovery, I did not initially think that this sungrazer would be it. It was only after discussing with other SOHO comet hunters, and counting through the most recent sungrazer discoveries, that the idea sunk in. I am honored to be part of such an amazing collaborative effort.

I'm super, SUPER excited to announce that on June 15th, the @ESA/@NASASun SOHO satellite made its 4,000th comet discovery!!

Many congrats to @TrygvePrestgard for finding the 4,000th comet, and a huge THANK YOU to all the citizen scientists who have contributed to the project! pic.twitter.com/FKJrlMIoKC

— Karl Battams (@SungrazerComets) June 17, 2020

Karl Battams, a space scientist at the U.S. Naval Research Lab in Washington, D.C., who works on SOHO and manages its comet-finding program, said:

Not only has SOHO rewritten the history books in terms of solar physics, but, unexpectedly, it’s rewritten the books in terms of comets as well.

NASA explained:

SOHO’s comet-hunting prowess comes from a combination of its long lifespan, its sensitive instruments focused on the solar corona, and the tireless work of citizen scientists who scour SOHO’s data for previously-undiscovered comets, which are clumps of frozen gases, rock and dust that orbit the sun.

The vast majority of comets found in SOHO’s data are from its coronagraph instrument, called LASCO, short for Large Angle and Spectrometric Coronagraph. Like other coronagraphs, LASCO uses a solid object – in this case, a metal disk – to block out the sun’s bright face, allowing its cameras to focus on the relatively faint outer atmosphere, the corona. The corona is critical to understanding how the sun’s changes propagate out into the solar system, making LASCO a key part of SOHO’s scientific quest to understand the sun and its influence.

But focusing on this faint region also means LASCO can do something other telescopes can’t – it can see comets flying extremely close to the sun, called sungrazers, which are otherwise blotted out by the sun’s intense light and impossible to see. This is why nearly all of SOHO’s 4,000 comet discoveries have come from LASCO’s data.

SOHO orbits the sun at the Lagrangian 1 point (L1) in the Earth-sun system. It’s about a million miles from Earth, and has an uninterrupted view from its vantage point between the sun and Earth. In this animation, Earth is blue, and the sun is yellow. The green dots are the L1 to L5 points: relativity stable places to park a (moving) spacecraft. Image via Wikimedia Commons.

Citizen scientist Trygve Prestgard, who has discovered around 120 previously-unknown comets using data from SOHO and NASA’s STEREO mission, commented:

I have been actively involved in the Sungrazer Project for about eight years … I enjoy the feeling of discovering something previously unknown, whether this is a nice ‘real time’ comet or a ‘long-gone’ overlooked one in the archives.

Read more about SOHO’s copious comets from NASA

The 4,000th comet discovered by the ESA/NASA SOHO sun observatory is seen here in an image from the spacecraft. Alongside is SOHO’s 3,999th comet discovery. The 2 comets are relatively close at approximately 1 million miles apart, suggesting that they could have been connected together as recently as a few years ago. Image via ESA/ NASA/ SOHO/ Karl Battams.

Bottom line: On June 15, 2020, citizen scientist Trygve Prestgard spotted a never-before-seen comet in data from the sun-observing SOHO spacecraft. It was SOHO’s 4,000th comet discovery.

Via NASA

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The NASA/ESA Solar and Heliospheric Observatory – affectionately called SOHO – is easily history’s greatest comet discoverer. This space observatory is designed to study the sun, but it now also has 4,000 comets to its credit, with the 4,000th discovered this week. SOHO’s abundance of comet discoveries is in part thanks to the dedication of citizen scientists, who pore through its data, seeking the moving fuzzballs near the sun that turn out to be sun-grazing comets. Amateur astronomer and geophysics graduate Trygve Prestgard – originally from Norway, now in Grenoble, France – spotted the 4,000th comet in the SOHO data on June 15, 2020. NASA reported:

The comet is nicknamed SOHO-4000, pending an official designation from the Minor Planet Center.

The 3,999th and 4,000th comets discovered by the SOHO spacecraft as they sped toward the sun. The spacecraft’s coronagraph, LASCO, uses a metal disk to block out the sun itself. This obscuring disk helps the instrument focus on the sun’s outer atmosphere or corona, and it allows SOHO to find comets! Image via ESA/ NASA/ SOHO/ Karl Battams.

Like most other SOHO-discovered comets, SOHO-4000 is part of the Kreutz family of sungrazers. The Kreutz family of comets all follow the same general trajectory, one that carries them skimming through the outer atmosphere of the sun. SOHO-4000 is on the small side, with a diameter in the range of 15-30 feet [4.5 to 9 meters], and it was extremely faint and close to the sun when discovered – meaning SOHO is the only observatory that has spotted the comet, as it’s impossible to see from Earth with or without a telescope.

Trygve Prestgard said:

I feel very fortunate to have found SOHO’s 4,000th comet. Although I knew that SOHO was nearing its 4,000th comet discovery, I did not initially think that this sungrazer would be it. It was only after discussing with other SOHO comet hunters, and counting through the most recent sungrazer discoveries, that the idea sunk in. I am honored to be part of such an amazing collaborative effort.

I'm super, SUPER excited to announce that on June 15th, the @ESA/@NASASun SOHO satellite made its 4,000th comet discovery!!

Many congrats to @TrygvePrestgard for finding the 4,000th comet, and a huge THANK YOU to all the citizen scientists who have contributed to the project! pic.twitter.com/FKJrlMIoKC

— Karl Battams (@SungrazerComets) June 17, 2020

Karl Battams, a space scientist at the U.S. Naval Research Lab in Washington, D.C., who works on SOHO and manages its comet-finding program, said:

Not only has SOHO rewritten the history books in terms of solar physics, but, unexpectedly, it’s rewritten the books in terms of comets as well.

NASA explained:

SOHO’s comet-hunting prowess comes from a combination of its long lifespan, its sensitive instruments focused on the solar corona, and the tireless work of citizen scientists who scour SOHO’s data for previously-undiscovered comets, which are clumps of frozen gases, rock and dust that orbit the sun.

The vast majority of comets found in SOHO’s data are from its coronagraph instrument, called LASCO, short for Large Angle and Spectrometric Coronagraph. Like other coronagraphs, LASCO uses a solid object – in this case, a metal disk – to block out the sun’s bright face, allowing its cameras to focus on the relatively faint outer atmosphere, the corona. The corona is critical to understanding how the sun’s changes propagate out into the solar system, making LASCO a key part of SOHO’s scientific quest to understand the sun and its influence.

But focusing on this faint region also means LASCO can do something other telescopes can’t – it can see comets flying extremely close to the sun, called sungrazers, which are otherwise blotted out by the sun’s intense light and impossible to see. This is why nearly all of SOHO’s 4,000 comet discoveries have come from LASCO’s data.

SOHO orbits the sun at the Lagrangian 1 point (L1) in the Earth-sun system. It’s about a million miles from Earth, and has an uninterrupted view from its vantage point between the sun and Earth. In this animation, Earth is blue, and the sun is yellow. The green dots are the L1 to L5 points: relativity stable places to park a (moving) spacecraft. Image via Wikimedia Commons.

Citizen scientist Trygve Prestgard, who has discovered around 120 previously-unknown comets using data from SOHO and NASA’s STEREO mission, commented:

I have been actively involved in the Sungrazer Project for about eight years … I enjoy the feeling of discovering something previously unknown, whether this is a nice ‘real time’ comet or a ‘long-gone’ overlooked one in the archives.

Read more about SOHO’s copious comets from NASA

The 4,000th comet discovered by the ESA/NASA SOHO sun observatory is seen here in an image from the spacecraft. Alongside is SOHO’s 3,999th comet discovery. The 2 comets are relatively close at approximately 1 million miles apart, suggesting that they could have been connected together as recently as a few years ago. Image via ESA/ NASA/ SOHO/ Karl Battams.

Bottom line: On June 15, 2020, citizen scientist Trygve Prestgard spotted a never-before-seen comet in data from the sun-observing SOHO spacecraft. It was SOHO’s 4,000th comet discovery.

Via NASA

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Sally Ride: 1st American woman in space

Sally Ride on the space shuttle Challenger in 1983. Image via NASA/ Mental Floss.

On June 18, 1983, physicist Sally Ride (1951-2012) became the first American woman to go into space, blasting off onboard the space shuttle Challenger for the STS-7 mission. Although it was a historic achievement for NASA, Ride was actually the third woman in space overall. Soviet cosmonaut Valentina Tereshkova was the first, in 1963, and fellow cosmonaut Svetlana Savitskaya was the second, in 1982. STS-7 was NASA’s seventh space shuttle mission and the second mission for Challenger.

Ride was selected as a mission specialist for the mission, after becoming eligible for space shuttle missions in 1979. She helped to operate the shuttle’s robotic arm, deploy the ANIK C-2 and PALAPA B-1 satellites, conduct the first formation flying of the shuttle with a free-flying satellite (SPAS-01), carry and operate the first U.S./ German cooperative materials science payload (OSTA-2), and operate the Continuous Flow Electrophoresis System (CFES) and the Monodisperse Latex Reactor (MLR) experiments. STS-7 also had the largest crew to fly in a single spacecraft up to that point (5 astronauts). Ride enjoyed the experience, saying simply:

The thing that I’ll remember most about the flight is that it was fun. In fact, I’m sure it was the most fun I’ll ever have in my life.

The crew of the STS-7 space shuttle Challenger mission in 1983. Front row, left to right: Sally K. Ride (mission specialist), Robert L. Crippen (commander), and Frederick H. Hauck (pilot). Back row, left to right: John M. Fabian and Norman E. Thagard (mission specialists). Image via NASA/ Wikipedia.

The mission lasted 6 days, 2 hours, 23 minutes, and 59 seconds, with Challenger landing on a lakebed runway at Edwards Air Force Base in California, on June 24, 1983.

The successful flight made Ride a hero for young women and girls, showing that they could break barriers that they previously might have thought to be impossible.

Ride later flew on the space shuttle again for mission STS-41G in 1984, the 13th shuttle flight overall. STS 41-G launched from Kennedy Space Center on October 5, 1984. She was also supposed to join shuttle mission STS-61M, but that mission was canceled due to the 1986 Challenger disaster.

Sally’s Story

Sally Ride was born in Los Angeles, California, on May 26, 1951. As a young girl, she was fascinated by science, and grew up playing with a telescope and chemistry set. As a teenager, she also loved sports such as running, volleyball, softball and, especially, tennis, winning a tennis scholarship to Westlake School for Girls in Los Angeles. After receiving undergraduate degrees in physics and in English from Stanford University in 1973, she obtained her Ph.D. in physics.

Portrait of Sally Ride. Image via NASA/ Wikipedia.

Sally Ride as a teenager. She was passionate about tennis and participated in national championships. Image via Afflictor.com.

In 1977, NASA was looking for new astronauts, including women. Ride saw an ad in the school newspaper inviting women to apply to the astronaut program and decided to apply. Out of 8,000 applicants, she was one of six women chosen as an astronaut candidate in January 1978. In 1979, she began training as a mission specialist for future space flights, which included parachute jumping, water survival, weightlessness, radio communications, and navigation. She was also part of the team that developed the robot arm used by shuttle crews to deploy and retrieve satellites.

In 1986, as part of the Rogers Commission, Ride later assisted in the investigation of the Challenger space shuttle disaster. According to a 2016 article in Popular Mechanics, it was Ride who revealed to General Donald Kutyna – another member of the Rogers Commission – that the O-rings used in the shuttle became stiff at low temperatures. This eventually led to the identification of the cause of the explosion that killed the seven astronauts. After the investigation was finished, she was assigned to NASA headquarters as special assistant to the administrator for long-range and strategic planning. She wrote an influential report entitled “Leadership and America’s Future in Space,” and became the first director of NASA’s Office of Exploration.

Ride retired from NASA in 1987, becoming a science fellow at the Center for International Security and Arms Control at Stanford University. She kept very busy in her post-astronaut career. In 1989, she became a professor of physics at the University of California, San Diego and director of the California Space Institute.

Sally Ride, left, and her partner, Tam O’Shaughnessy, discuss the role of women in science and Earth’s changing climate during a 2008 American Library Association conference in Anaheim, California, in 2008. Image via American Library Association/ NBC News.

President Obama greets former astronaut Sally Ride prior to the launch of the “Educate to Innovate” Campaign for Excellence in Science, Technology, Engineering & Math (STEM) Education, in the South Court Auditorium of the White House, Nov. 23, 2009. Image via Pete Souza/ White House/ Obama White House Archives.

In 2001, she founded Sally Ride Science, a company she co-founded with her partner, Tam O’Shaughnessy, to inspire other young women to pursue STEM careers. Her company targeted middle school students and their parents. Ride wrote seven science books for children, including To Space and Back (with Sue Okie); Voyager; The Third Planet; The Mystery of Mars; Exploring Our Solar System; Mission Planet Earth; and Mission Save the Planet (all with Tam O’Shaughnessy).

Ride died on July 23, 2012, after a 17-month battle with pancreatic cancer. In November 2013, she was posthumously awarded the Presidential Medal of Freedom in a White House ceremony. O’Shaughnessy accepted the medal on her behalf. Sally’s mother, Joyce Ride, and her sister, Bear Ride, attended along with other 2013 medal recipients including President Bill Clinton, Gloria Steinem, and Oprah Winfrey. She will always be remembered as a true pioneer for female astronauts and women in science.

Bottom line: Sally Ride became the first American woman to go into space on June 18, 1983.

Read Sally Ride’s biography from NASA

Read more about her at Sally Ride Science

from EarthSky https://ift.tt/3fBtC1X

Sally Ride on the space shuttle Challenger in 1983. Image via NASA/ Mental Floss.

On June 18, 1983, physicist Sally Ride (1951-2012) became the first American woman to go into space, blasting off onboard the space shuttle Challenger for the STS-7 mission. Although it was a historic achievement for NASA, Ride was actually the third woman in space overall. Soviet cosmonaut Valentina Tereshkova was the first, in 1963, and fellow cosmonaut Svetlana Savitskaya was the second, in 1982. STS-7 was NASA’s seventh space shuttle mission and the second mission for Challenger.

Ride was selected as a mission specialist for the mission, after becoming eligible for space shuttle missions in 1979. She helped to operate the shuttle’s robotic arm, deploy the ANIK C-2 and PALAPA B-1 satellites, conduct the first formation flying of the shuttle with a free-flying satellite (SPAS-01), carry and operate the first U.S./ German cooperative materials science payload (OSTA-2), and operate the Continuous Flow Electrophoresis System (CFES) and the Monodisperse Latex Reactor (MLR) experiments. STS-7 also had the largest crew to fly in a single spacecraft up to that point (5 astronauts). Ride enjoyed the experience, saying simply:

The thing that I’ll remember most about the flight is that it was fun. In fact, I’m sure it was the most fun I’ll ever have in my life.

The crew of the STS-7 space shuttle Challenger mission in 1983. Front row, left to right: Sally K. Ride (mission specialist), Robert L. Crippen (commander), and Frederick H. Hauck (pilot). Back row, left to right: John M. Fabian and Norman E. Thagard (mission specialists). Image via NASA/ Wikipedia.

The mission lasted 6 days, 2 hours, 23 minutes, and 59 seconds, with Challenger landing on a lakebed runway at Edwards Air Force Base in California, on June 24, 1983.

The successful flight made Ride a hero for young women and girls, showing that they could break barriers that they previously might have thought to be impossible.

Ride later flew on the space shuttle again for mission STS-41G in 1984, the 13th shuttle flight overall. STS 41-G launched from Kennedy Space Center on October 5, 1984. She was also supposed to join shuttle mission STS-61M, but that mission was canceled due to the 1986 Challenger disaster.

Sally’s Story

Sally Ride was born in Los Angeles, California, on May 26, 1951. As a young girl, she was fascinated by science, and grew up playing with a telescope and chemistry set. As a teenager, she also loved sports such as running, volleyball, softball and, especially, tennis, winning a tennis scholarship to Westlake School for Girls in Los Angeles. After receiving undergraduate degrees in physics and in English from Stanford University in 1973, she obtained her Ph.D. in physics.

Portrait of Sally Ride. Image via NASA/ Wikipedia.

Sally Ride as a teenager. She was passionate about tennis and participated in national championships. Image via Afflictor.com.

In 1977, NASA was looking for new astronauts, including women. Ride saw an ad in the school newspaper inviting women to apply to the astronaut program and decided to apply. Out of 8,000 applicants, she was one of six women chosen as an astronaut candidate in January 1978. In 1979, she began training as a mission specialist for future space flights, which included parachute jumping, water survival, weightlessness, radio communications, and navigation. She was also part of the team that developed the robot arm used by shuttle crews to deploy and retrieve satellites.

In 1986, as part of the Rogers Commission, Ride later assisted in the investigation of the Challenger space shuttle disaster. According to a 2016 article in Popular Mechanics, it was Ride who revealed to General Donald Kutyna – another member of the Rogers Commission – that the O-rings used in the shuttle became stiff at low temperatures. This eventually led to the identification of the cause of the explosion that killed the seven astronauts. After the investigation was finished, she was assigned to NASA headquarters as special assistant to the administrator for long-range and strategic planning. She wrote an influential report entitled “Leadership and America’s Future in Space,” and became the first director of NASA’s Office of Exploration.

Ride retired from NASA in 1987, becoming a science fellow at the Center for International Security and Arms Control at Stanford University. She kept very busy in her post-astronaut career. In 1989, she became a professor of physics at the University of California, San Diego and director of the California Space Institute.

Sally Ride, left, and her partner, Tam O’Shaughnessy, discuss the role of women in science and Earth’s changing climate during a 2008 American Library Association conference in Anaheim, California, in 2008. Image via American Library Association/ NBC News.

President Obama greets former astronaut Sally Ride prior to the launch of the “Educate to Innovate” Campaign for Excellence in Science, Technology, Engineering & Math (STEM) Education, in the South Court Auditorium of the White House, Nov. 23, 2009. Image via Pete Souza/ White House/ Obama White House Archives.

In 2001, she founded Sally Ride Science, a company she co-founded with her partner, Tam O’Shaughnessy, to inspire other young women to pursue STEM careers. Her company targeted middle school students and their parents. Ride wrote seven science books for children, including To Space and Back (with Sue Okie); Voyager; The Third Planet; The Mystery of Mars; Exploring Our Solar System; Mission Planet Earth; and Mission Save the Planet (all with Tam O’Shaughnessy).

Ride died on July 23, 2012, after a 17-month battle with pancreatic cancer. In November 2013, she was posthumously awarded the Presidential Medal of Freedom in a White House ceremony. O’Shaughnessy accepted the medal on her behalf. Sally’s mother, Joyce Ride, and her sister, Bear Ride, attended along with other 2013 medal recipients including President Bill Clinton, Gloria Steinem, and Oprah Winfrey. She will always be remembered as a true pioneer for female astronauts and women in science.

Bottom line: Sally Ride became the first American woman to go into space on June 18, 1983.

Read Sally Ride’s biography from NASA

Read more about her at Sally Ride Science

from EarthSky https://ift.tt/3fBtC1X

Picking out the sound of tumours

For the longest time, scientists have been trying to find ways to use blood to better understand how cancer progresses inside the body.

As a tumour grows inside the body, it releases DNA into the bloodstream. And over the last decade, this circulating tumour DNA (ctDNA) has been the focus of researchers aiming to detect or monitor cancer.

This technique (known as a liquid biopsy) allows doctors to find out more about a patient’s cancer without the need for surgery. Although these ctDNA-based tests aren’t yet common, their use has been rapidly growing over the last few years.

The potential benefits are huge, both for designing clinical trials and for patients. Monitoring patients – particularly after they’ve received treatment – allows doctors to assess if treatment was successful and monitor for signs that the cancer might return.

Now, a team of Cancer Research UK scientists led by Dr Nitzan Rosenfeld at the University of Cambridge have developed a new experimental liquid biopsy that is up to ten times more sensitive than those being tested currently and has the potential to change how cancer is treated.

Cancelling out the noise

We’ve blogged before about the challenges with developing a blood test to pick up cancer. And a big issue is the complexity of changes to cancer cell’s DNA.

Cancer isn’t caused by just one error, it’s a culmination of many mutations that will vary from cancer to cancer and person to person. One of the ways that researchers can get around this complexity problem is to make the test more tailored. By analysing the individual genetic makeup of a person’s tumour, liquid biopsies can home in on a specific set of mutations and use them as a starting point to monitor the progression of cancer.

But knowing what to look for is just the start – because these tiny fragments of tumour DNA aren’t alone in the blood, they’re floating amongst millions of fragments of DNA from other cells.

Various methods have been proposed to reduce noise and improve signal to noise. In the last few months there’s been an explosion of methods that are based on tumour-informed analysis and personalized panels, with several exciting advances presented or published very recently.

– Dr Nitzan Rosenfeld

Scientists have worked to cut through this noise by looking for more than one DNA error, designing tests that pick up anything between 10 and 100 mutations. Using this approach, some tests are able to detect 1 mutant molecule amongst 30,000 pieces of DNA. But while the numbers seem impressive, they’re not good enough – particularly when there’s only a tube of blood to work with. This insensitivity means that even if the patient has enough cancer in their body to lead to a potential relapse, the test can come back negative.

Rosenfeld’s team thought they could do better.

According to Dr Rosenfeld this came about by “a combination of developing a lab process, which generates data from patient samples and control samples, and computational methods that have been developed to take advantage of the dataset that this generates”

The key was to combine data generated from personally profiling a patient’s tumour (looking for hundreds and sometimes thousands of mutations in each blood sample) with a clever computational solution.

It’s like listening to a quiet song on a pair of noise-cancelling headphones. Their new computational technique uses their data to “learn” the pattern of background noise – the molecular equivalent of a crowded street – in order to filter it out and better analyse the mutations that have been made clearer.

This uses control data to “learn” the pattern of background noise, and a series of filters and statistical methods that remove noise, define the detection classification algorithms and improve their confidence margins

– Dr Nitzan Rosenfeld

Putting their new techniques to the test on samples from 105 cancer patients, across 5 different cancer types and multiple stages of disease, they found the new technique was able to detect ctDNA at high sensitivity in patients with advanced breast and melanoma cancer, as well as patients with glioblastoma (a cancer traditionally difficult to detect in blood).

Compared to the traditional techniques, this new method can pick up 1 mutant molecule in amongst 100,000 – 1,000,000 pieces of DNA.

This sensitivity boost meant the test could detect tumour DNA in the blood of patients with earlier stage disease, included patients with early-stage lung and breast cancers, as well as those who had already undergone surgery for melanoma, despite the levels being much lower and more difficult to find.

Monitoring the future

Although it might be several years before this type of approach is ready to be used with patients, the team are still excited by what might come.

Further increases in sensitivity could lead to tests that would only require a drop of blood – meaning that patients could do it at home and send it off to the lab themselves. This would allow for more patients to have their cancers more continually monitored while not having to go to as many hospital appointments.

In future studies, the team and their collaborators plan to use this technique to measure ctDNA levels in people who are at high risk of developing cancer and hope that the information they will generate can be used to help refine future tests for cancer early detection.

Alex

Reference

Wan, J.C.M., Heider, K., Gale, D., Murphy, S., Fisher, E., Mouliere, F., Ruiz-Valdepenas, A., Santonja, A., Morris, J., Chandrananda, D., Marshall, A., Gill, A.B., Chan, P.Y., Barker, E., Young, G., Cooper, W.N., Hudecova, I., Marass, F., Mair, R., Brindle, K.M., Stewart, G.D., Abraham, J.E., Caldas, C., Rassl, D.M., Rintoul, R.C., Alifrangis, C., Middleton, M.R., Gallagher, F.A., Parkinson, C., Durrani, A., McDermott, U., Smith, C.G., Massie, C., Corrie, P.G., Rosenfeld, N., 2020. ctDNA monitoring using patient-specific sequencing and integration of variant reads. Science Translational Medicine 12, eaaz8084. https://doi.org/10.1126/scitranslmed.aaz8084

from Cancer Research UK – Science blog https://ift.tt/2Vc1Hht

For the longest time, scientists have been trying to find ways to use blood to better understand how cancer progresses inside the body.

As a tumour grows inside the body, it releases DNA into the bloodstream. And over the last decade, this circulating tumour DNA (ctDNA) has been the focus of researchers aiming to detect or monitor cancer.

This technique (known as a liquid biopsy) allows doctors to find out more about a patient’s cancer without the need for surgery. Although these ctDNA-based tests aren’t yet common, their use has been rapidly growing over the last few years.

The potential benefits are huge, both for designing clinical trials and for patients. Monitoring patients – particularly after they’ve received treatment – allows doctors to assess if treatment was successful and monitor for signs that the cancer might return.

Now, a team of Cancer Research UK scientists led by Dr Nitzan Rosenfeld at the University of Cambridge have developed a new experimental liquid biopsy that is up to ten times more sensitive than those being tested currently and has the potential to change how cancer is treated.

Cancelling out the noise

We’ve blogged before about the challenges with developing a blood test to pick up cancer. And a big issue is the complexity of changes to cancer cell’s DNA.

Cancer isn’t caused by just one error, it’s a culmination of many mutations that will vary from cancer to cancer and person to person. One of the ways that researchers can get around this complexity problem is to make the test more tailored. By analysing the individual genetic makeup of a person’s tumour, liquid biopsies can home in on a specific set of mutations and use them as a starting point to monitor the progression of cancer.

But knowing what to look for is just the start – because these tiny fragments of tumour DNA aren’t alone in the blood, they’re floating amongst millions of fragments of DNA from other cells.

Various methods have been proposed to reduce noise and improve signal to noise. In the last few months there’s been an explosion of methods that are based on tumour-informed analysis and personalized panels, with several exciting advances presented or published very recently.

– Dr Nitzan Rosenfeld

Scientists have worked to cut through this noise by looking for more than one DNA error, designing tests that pick up anything between 10 and 100 mutations. Using this approach, some tests are able to detect 1 mutant molecule amongst 30,000 pieces of DNA. But while the numbers seem impressive, they’re not good enough – particularly when there’s only a tube of blood to work with. This insensitivity means that even if the patient has enough cancer in their body to lead to a potential relapse, the test can come back negative.

Rosenfeld’s team thought they could do better.

According to Dr Rosenfeld this came about by “a combination of developing a lab process, which generates data from patient samples and control samples, and computational methods that have been developed to take advantage of the dataset that this generates”

The key was to combine data generated from personally profiling a patient’s tumour (looking for hundreds and sometimes thousands of mutations in each blood sample) with a clever computational solution.

It’s like listening to a quiet song on a pair of noise-cancelling headphones. Their new computational technique uses their data to “learn” the pattern of background noise – the molecular equivalent of a crowded street – in order to filter it out and better analyse the mutations that have been made clearer.

This uses control data to “learn” the pattern of background noise, and a series of filters and statistical methods that remove noise, define the detection classification algorithms and improve their confidence margins

– Dr Nitzan Rosenfeld

Putting their new techniques to the test on samples from 105 cancer patients, across 5 different cancer types and multiple stages of disease, they found the new technique was able to detect ctDNA at high sensitivity in patients with advanced breast and melanoma cancer, as well as patients with glioblastoma (a cancer traditionally difficult to detect in blood).

Compared to the traditional techniques, this new method can pick up 1 mutant molecule in amongst 100,000 – 1,000,000 pieces of DNA.

This sensitivity boost meant the test could detect tumour DNA in the blood of patients with earlier stage disease, included patients with early-stage lung and breast cancers, as well as those who had already undergone surgery for melanoma, despite the levels being much lower and more difficult to find.

Monitoring the future

Although it might be several years before this type of approach is ready to be used with patients, the team are still excited by what might come.

Further increases in sensitivity could lead to tests that would only require a drop of blood – meaning that patients could do it at home and send it off to the lab themselves. This would allow for more patients to have their cancers more continually monitored while not having to go to as many hospital appointments.

In future studies, the team and their collaborators plan to use this technique to measure ctDNA levels in people who are at high risk of developing cancer and hope that the information they will generate can be used to help refine future tests for cancer early detection.

Alex

Reference

Wan, J.C.M., Heider, K., Gale, D., Murphy, S., Fisher, E., Mouliere, F., Ruiz-Valdepenas, A., Santonja, A., Morris, J., Chandrananda, D., Marshall, A., Gill, A.B., Chan, P.Y., Barker, E., Young, G., Cooper, W.N., Hudecova, I., Marass, F., Mair, R., Brindle, K.M., Stewart, G.D., Abraham, J.E., Caldas, C., Rassl, D.M., Rintoul, R.C., Alifrangis, C., Middleton, M.R., Gallagher, F.A., Parkinson, C., Durrani, A., McDermott, U., Smith, C.G., Massie, C., Corrie, P.G., Rosenfeld, N., 2020. ctDNA monitoring using patient-specific sequencing and integration of variant reads. Science Translational Medicine 12, eaaz8084. https://doi.org/10.1126/scitranslmed.aaz8084

from Cancer Research UK – Science blog https://ift.tt/2Vc1Hht