Science Surgery: ‘Why do some cancer treatments stop working after so long?’

Our Science Surgery series answers your cancer questions.

Cancer treatments can work in lots of different ways, aiming to kill tumour cells or keep them under control. Ideally they cause tumours to shrink, but drugs can also be considered successful if they stop tumours growing.

But unfortunately, the effects don’t always last forever. Sometimes a drug can have an initial effect on a cancer’s size or growth, but then the tumour starts to grow again despite treatment. This is what’s known as drug resistance.

“No matter what amazing new treatments we come up with, eventually at least some patients’ tumours will become resistant to them, that is the reality”, says Dr Georgina Sava, a research associate working on drug resistance in breast cancer in Professor Simak Ali’s lab at Imperial College London.

Sava tries to predict ways that resistance may develop to new drugs, aiming to stay one step ahead of the cancer. She says drug resistance is a big problem in cancer and there are lots of people working to understand how and why it happens.

Resistance comes about because of faults in the DNA of cancer cells. We’ve blogged before about how cells first become cancerous. And it turns out the same processes can help a cancer evolve and adapt to treatments.

Some of the changes that arise can mean cells stop responding to cancer drugs like chemotherapy, targeted cancer drugs or hormone therapy.

Cancer cells can keep evolving

Cancer cells develop from normal cells because of a build up of mistakes in key parts of our DNA. But it doesn’t stop there. Even when a cell has become cancerous, DNA faults continue to appear. Some of these faults can make the cells resistant to a treatment.

Individual cells in a tumour can have different DNA faults and, as a result, not every cancer cell in a tumour is exactly the same. This is where problems arise.

“When cancer cells are treated with a drug, it’s like survival of the fittest,” says Sava. “in an ideal situation, every cell in a tumour would be killed. But, if even a single cell happens to be resistant to the drug, it will survive and eventually grow to become a new tumour.”

This is problematic because it can be hard to detect any lingering resistant cells, particularly if there are very few of them.

“Once a resistant tumour has developed in this way, the drug that was once able to shrink the tumour, will no longer work,” Sava adds.

How do drugs stop working?

There are lots of ways that cancer cells can become resistant to a drug.

Sava highlighted the problem of resistance to hormone therapies, which are used to treat some breast cancers that are driven by the hormone oestrogen.

Oestrogen can interact with oestrogen receptors on the surface of breast cancer cells, signalling them to grow. Hormone therapies work by either blocking this interaction, or by lowering the levels of oestrogen in the body.

But cancer cells can become resistant to these therapies if they develop a specific fault in the oestrogen receptor, which means it no longer needs oestrogen to signal breast cancer cells to divide.

When this happens, hormone therapies will no longer work.

The same is true for other drugs, like chemotherapy. Cancer cells can develop a number of different faults that help them avoid the effects of chemotherapy. This includes DNA changes that:

• stop drugs getting into the cell in the first place;
• hastily pump the treatments back out before they can cause any damage; or
• help cells quickly repair DNA damaged by chemotherapy.

Resisting resistance

Scientists like Sava are working hard to overcome drug resistance.

“One of the main ways that we can try to overcome drug resistance is by using combination treatments.” By hitting the cancer in multiple ways at the same time using different drugs, Sava says cancer cells have less options to escape.

But it would also be helpful to be able to predict how a treatment might stop working, which is exactly what Sava is aiming to do in breast cancer.

Sava takes breast cancer cells and exposes them to a drug for long periods of time, to mimic a patient taking a drug.

“The cells initially stop growing and die. But after months of treatment, they start growing again and we can see that they’ve become resistant to the drug. We can then compare these resistant cells to the original ones that were sensitive to the drug and work out how they’ve adapted to become resistant.”

In Sava’s case, she found that the resistant cells had started to produce abnormally high levels of a cellular pump, called p-glycoprotein, which protects cells by preventing drugs from getting in.

Researchers have been looking at drug resistance for almost as long as they have used cancer drugs. To make cancer drug treatments more effective, scientists like Sava need to find a way of overcoming resistance.

“We are constantly improving our understanding of drug resistance, which is paving the way for better treatment for patients,” says Sava.

Ethan

If you’d like to ask us something, post a comment below or email sciencesurgery@cancer.org.uk with your question and first name.

from Cancer Research UK – Science blog https://ift.tt/2MJDj3Z

Our Science Surgery series answers your cancer questions.

Cancer treatments can work in lots of different ways, aiming to kill tumour cells or keep them under control. Ideally they cause tumours to shrink, but drugs can also be considered successful if they stop tumours growing.

But unfortunately, the effects don’t always last forever. Sometimes a drug can have an initial effect on a cancer’s size or growth, but then the tumour starts to grow again despite treatment. This is what’s known as drug resistance.

“No matter what amazing new treatments we come up with, eventually at least some patients’ tumours will become resistant to them, that is the reality”, says Dr Georgina Sava, a research associate working on drug resistance in breast cancer in Professor Simak Ali’s lab at Imperial College London.

Sava tries to predict ways that resistance may develop to new drugs, aiming to stay one step ahead of the cancer. She says drug resistance is a big problem in cancer and there are lots of people working to understand how and why it happens.

Resistance comes about because of faults in the DNA of cancer cells. We’ve blogged before about how cells first become cancerous. And it turns out the same processes can help a cancer evolve and adapt to treatments.

Some of the changes that arise can mean cells stop responding to cancer drugs like chemotherapy, targeted cancer drugs or hormone therapy.

Cancer cells can keep evolving

Cancer cells develop from normal cells because of a build up of mistakes in key parts of our DNA. But it doesn’t stop there. Even when a cell has become cancerous, DNA faults continue to appear. Some of these faults can make the cells resistant to a treatment.

Individual cells in a tumour can have different DNA faults and, as a result, not every cancer cell in a tumour is exactly the same. This is where problems arise.

“When cancer cells are treated with a drug, it’s like survival of the fittest,” says Sava. “in an ideal situation, every cell in a tumour would be killed. But, if even a single cell happens to be resistant to the drug, it will survive and eventually grow to become a new tumour.”

This is problematic because it can be hard to detect any lingering resistant cells, particularly if there are very few of them.

“Once a resistant tumour has developed in this way, the drug that was once able to shrink the tumour, will no longer work,” Sava adds.

How do drugs stop working?

There are lots of ways that cancer cells can become resistant to a drug.

Sava highlighted the problem of resistance to hormone therapies, which are used to treat some breast cancers that are driven by the hormone oestrogen.

Oestrogen can interact with oestrogen receptors on the surface of breast cancer cells, signalling them to grow. Hormone therapies work by either blocking this interaction, or by lowering the levels of oestrogen in the body.

But cancer cells can become resistant to these therapies if they develop a specific fault in the oestrogen receptor, which means it no longer needs oestrogen to signal breast cancer cells to divide.

When this happens, hormone therapies will no longer work.

The same is true for other drugs, like chemotherapy. Cancer cells can develop a number of different faults that help them avoid the effects of chemotherapy. This includes DNA changes that:

• stop drugs getting into the cell in the first place;
• hastily pump the treatments back out before they can cause any damage; or
• help cells quickly repair DNA damaged by chemotherapy.

Resisting resistance

Scientists like Sava are working hard to overcome drug resistance.

“One of the main ways that we can try to overcome drug resistance is by using combination treatments.” By hitting the cancer in multiple ways at the same time using different drugs, Sava says cancer cells have less options to escape.

But it would also be helpful to be able to predict how a treatment might stop working, which is exactly what Sava is aiming to do in breast cancer.

Sava takes breast cancer cells and exposes them to a drug for long periods of time, to mimic a patient taking a drug.

“The cells initially stop growing and die. But after months of treatment, they start growing again and we can see that they’ve become resistant to the drug. We can then compare these resistant cells to the original ones that were sensitive to the drug and work out how they’ve adapted to become resistant.”

In Sava’s case, she found that the resistant cells had started to produce abnormally high levels of a cellular pump, called p-glycoprotein, which protects cells by preventing drugs from getting in.

Researchers have been looking at drug resistance for almost as long as they have used cancer drugs. To make cancer drug treatments more effective, scientists like Sava need to find a way of overcoming resistance.

“We are constantly improving our understanding of drug resistance, which is paving the way for better treatment for patients,” says Sava.

Ethan

If you’d like to ask us something, post a comment below or email sciencesurgery@cancer.org.uk with your question and first name.

from Cancer Research UK – Science blog https://ift.tt/2MJDj3Z

Name NASA’s next Mars rover!

NASA is inviting students to name the next Mars rover. The Mars 2020 Rover is preparing to launch in July 2020, but it doesn’t have a name yet.

NASA’s Name the Rover contest asks K-12 students across the United States to send in short essays with their best name ideas.

The contest started on August 27 and runs until November 1. K-12 students in U.S. public, private and home schools can enter.

The grand prize winner will name the rover and be invited to see the spacecraft launch in July 2020 from Cape Canaveral Air Force Station in Florida.

Complete contest and prize details here.

The Mars 2020 rover is a 2,300-pound (1,040-kilogram) robotic scientist that will search for signs of past microbial life, characterize the planet’s climate and geology, collect samples for future return to Earth, and pave the way for human exploration of the Red Planet.

Building NASA’s Mars 2020 Rover: See NASA’s next Mars rover quite literally coming together inside a clean room at the Jet Propulsion Laboratory.

NASA Administrator Jim Bridenstine said:

Our Mars 2020 rover has fully taken shape over the past several months … All that’s missing is a great name!

To enter the contest, students must submit by November 1 their proposed rover name and a short essay, no more than 150 words, explaining why their proposed name should be chosen. The essays will be divided into three groups, by grade level — K-4, 5-8, and 9-12 — and judged on the appropriateness, significance and originality of their proposed name, and the originality and quality of their essay, and/or finalist interview presentation.

Fifty-two semifinalists will be selected per group, each representing their respective state or U.S. territory. Three finalists then will be selected from each group to advance to the final round.

As part of the final selection process, the public will have an opportunity to vote online on the nine finalists in January 2020. NASA plans to announce the selected name on February 18, 2020 — exactly one year before the rover will land on the surface of Mars.

Complete contest and prize details here.

If you’re a U.S. resident over 18 years old, you can volunteer to help judge the thousands of contest entries that NASA anticipated to pour in from around the country. Here’s how.

Bottom line: A NASA contest invites U.S. students to come up with a name for the 2020 Mars Rover.

Via NASA

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

NASA is inviting students to name the next Mars rover. The Mars 2020 Rover is preparing to launch in July 2020, but it doesn’t have a name yet.

NASA’s Name the Rover contest asks K-12 students across the United States to send in short essays with their best name ideas.

The contest started on August 27 and runs until November 1. K-12 students in U.S. public, private and home schools can enter.

The grand prize winner will name the rover and be invited to see the spacecraft launch in July 2020 from Cape Canaveral Air Force Station in Florida.

Complete contest and prize details here.

The Mars 2020 rover is a 2,300-pound (1,040-kilogram) robotic scientist that will search for signs of past microbial life, characterize the planet’s climate and geology, collect samples for future return to Earth, and pave the way for human exploration of the Red Planet.

Building NASA’s Mars 2020 Rover: See NASA’s next Mars rover quite literally coming together inside a clean room at the Jet Propulsion Laboratory.

NASA Administrator Jim Bridenstine said:

Our Mars 2020 rover has fully taken shape over the past several months … All that’s missing is a great name!

To enter the contest, students must submit by November 1 their proposed rover name and a short essay, no more than 150 words, explaining why their proposed name should be chosen. The essays will be divided into three groups, by grade level — K-4, 5-8, and 9-12 — and judged on the appropriateness, significance and originality of their proposed name, and the originality and quality of their essay, and/or finalist interview presentation.

Fifty-two semifinalists will be selected per group, each representing their respective state or U.S. territory. Three finalists then will be selected from each group to advance to the final round.

As part of the final selection process, the public will have an opportunity to vote online on the nine finalists in January 2020. NASA plans to announce the selected name on February 18, 2020 — exactly one year before the rover will land on the surface of Mars.

Complete contest and prize details here.

If you’re a U.S. resident over 18 years old, you can volunteer to help judge the thousands of contest entries that NASA anticipated to pour in from around the country. Here’s how.

Bottom line: A NASA contest invites U.S. students to come up with a name for the 2020 Mars Rover.

Via NASA

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

Gaia tracks sibling stars in Milky Way

Stars are born in huge clouds of gas and dust in space. As we look out into our Milky Way galaxy, we see some stars that are still hanging out in their original star families; we say these stars reside in open star clusters. Our sun was surely born in such a cloud, whose stars have now dispersed into the Milky Way at large, moving with the general stream of stars around the galaxy’s center. The search for the sun’s lost siblings is ongoing. But what if we could recognize not just our sun’s siblings but sibling stars across a wide expanse of the Milky Way? In fact, we can. The amazing Gaia spacecraft of the European Space Agency (ESA) has given us that ability. And, contrary to what astronomers believed – rather than leaving home young, as expected – the star siblings revealed by Gaia have been found to stick together in long-lasting star groups. Astronomers are currently referring to these groups of star siblings as “strings.”

An August 28, 2019, statement from ESA explained why information about star families or strings has been so long in coming:

Exploring the distribution and past history of the starry residents of our galaxy is especially challenging as it requires astronomers to determine the ages of stars. This is not at all trivial, as ‘average’ stars of a similar mass but different ages look very much alike.

To figure out when a star formed, astronomers must instead look at populations of stars thought to have formed at the same time – but knowing which stars are siblings poses a further challenge, since stars do not necessarily hang out long in the stellar cradles where they formed.

A face-on view of star families – sibling stars born from a single cloud of gas – in our Milky Way galaxy, within 3,000 light-years of our sun (center of image). The Milky Way is 100,000 light-years wide. Stars in clusters today appear as dots. Co-moving groups – stars born together and still moving together in space – appear as thick lines. The diagram is based on data from the astoundingly useful second data release of the European Space Agency’s Gaia mission. Image via M. Kounkel & K. Covey (2019).

Marina Kounkel of Western Washington University is lead author of the new peer-reviewed study, which was published August 23, 2019, in The Astronomical Journal. She explained:

To identify which stars formed together, we look for stars moving similarly, as all of the stars that formed within the same cloud or cluster would move in a similar way.

We knew of a few such ‘co-moving’ star groups near the solar system, but Gaia enabled us to explore the Milky Way in great detail out to far greater distances, revealing many more of these groups.

Kounkel used data from Gaia’s second data release in April 2018 to trace the structure and star formation activity of an area of space surrounding our solar system, and to explore how this changed over time. This data release lists the motions and positions of over a billion stars with a precision made possible only since Gaia’s launch in 2013. Gaia has been using the unglamorous-sounding tool of astrometry to do something quite amazing. The satellite is charting a three-dimensional map of our galaxy, pinpointing the locations, motions, and dynamics of Milky Way stars, along with additional information about many of these stars. I can’t emphasize enough how Gaia is making possible a view of the Milky Way we never had before. As regards this study, ESA said:

The analysis of the Gaia data, relying on a machine-learning algorithm, uncovered nearly 2,000 previously unidentified clusters and co-moving groups of stars up to about 3,000 light years from us – roughly 750 times the distance to Proxima Centauri, the nearest star to the sun.

The study also determined the ages for hundreds of thousands of stars, making it possible to track stellar ‘families’ and uncover their surprising arrangements.

Stellar families in Gaia’s sky. Image via ESA/Gaia/DPAC; Data: M. Kounkel & K. Covey (2019).

Kounkel added:

Around half of these stars are found in long, string-like configurations that mirror features present within their giant birth clouds.

We generally thought young stars would leave their birth sites just a few million years after they form, completely losing ties with their original family – but it seems that stars can stay close to their siblings for as long as a few billion years.

And here’s another interesting fact about these star strings, as revealed by Gaia:

The strings also appear to be oriented in particular ways with respect to our galaxy’s spiral arms – something that depends upon the ages of the stars within a string. This is especially evident for the youngest strings, comprising stars younger than 100 million years, which tend to be oriented at right angles to the spiral arm nearest to our solar system.

The astronomers suspect that the older strings of stars must have been perpendicular to the spiral arms that existed when these stars formed, which have now been reshuffled over the past billion years.

Kevin Covey, also of Western Washington University, is a study co-author. He said:

The proximity and orientation of the youngest strings to the Milky Way’s present-day spiral arms shows that older strings are an important ‘fossil record’ of our galaxy’s spiral structure.

The nature of spiral arms is still debated, with the verdict on them being stable or dynamic structures not settled yet. Studying these older strings will help us understand if the arms are mostly static, or if they move or dissipate and re-form over the course of a few hundred million years – roughly the time it takes for the sun to orbit around the galactic center a couple of times.

Further Gaia releases, including more and increasingly precise data, are planned for the coming decade, providing astronomers with the information they need to unfold the star-formation history of our galaxy. Timo Prusti, Gaia project scientist at ESA, said:

Gaia is a truly ground-breaking mission that is revealing the history of the Milky Way – and its constituent stars – like never before.

If you’ve been following Gaia, you’ll agree!

An edge-on view of stellar groups and strings in our Milky Way galaxy. Image via M. Kounkel & K. Covey (2019).

Bottom line: A new analysis of data from Gaia’s second data release has revealed that star siblings – stars born from the same cloud of gas and dust in space – stick together in long-lasting star groups moving around the center of the Milky Way. Astronomers are referring to these groups as “strings.”

Source: Untangling the Galaxy. I. Local Structure and Star Formation History of the Milky Way

Via ESA

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

Stars are born in huge clouds of gas and dust in space. As we look out into our Milky Way galaxy, we see some stars that are still hanging out in their original star families; we say these stars reside in open star clusters. Our sun was surely born in such a cloud, whose stars have now dispersed into the Milky Way at large, moving with the general stream of stars around the galaxy’s center. The search for the sun’s lost siblings is ongoing. But what if we could recognize not just our sun’s siblings but sibling stars across a wide expanse of the Milky Way? In fact, we can. The amazing Gaia spacecraft of the European Space Agency (ESA) has given us that ability. And, contrary to what astronomers believed – rather than leaving home young, as expected – the star siblings revealed by Gaia have been found to stick together in long-lasting star groups. Astronomers are currently referring to these groups of star siblings as “strings.”

An August 28, 2019, statement from ESA explained why information about star families or strings has been so long in coming:

Exploring the distribution and past history of the starry residents of our galaxy is especially challenging as it requires astronomers to determine the ages of stars. This is not at all trivial, as ‘average’ stars of a similar mass but different ages look very much alike.

To figure out when a star formed, astronomers must instead look at populations of stars thought to have formed at the same time – but knowing which stars are siblings poses a further challenge, since stars do not necessarily hang out long in the stellar cradles where they formed.

A face-on view of star families – sibling stars born from a single cloud of gas – in our Milky Way galaxy, within 3,000 light-years of our sun (center of image). The Milky Way is 100,000 light-years wide. Stars in clusters today appear as dots. Co-moving groups – stars born together and still moving together in space – appear as thick lines. The diagram is based on data from the astoundingly useful second data release of the European Space Agency’s Gaia mission. Image via M. Kounkel & K. Covey (2019).

Marina Kounkel of Western Washington University is lead author of the new peer-reviewed study, which was published August 23, 2019, in The Astronomical Journal. She explained:

To identify which stars formed together, we look for stars moving similarly, as all of the stars that formed within the same cloud or cluster would move in a similar way.

We knew of a few such ‘co-moving’ star groups near the solar system, but Gaia enabled us to explore the Milky Way in great detail out to far greater distances, revealing many more of these groups.

Kounkel used data from Gaia’s second data release in April 2018 to trace the structure and star formation activity of an area of space surrounding our solar system, and to explore how this changed over time. This data release lists the motions and positions of over a billion stars with a precision made possible only since Gaia’s launch in 2013. Gaia has been using the unglamorous-sounding tool of astrometry to do something quite amazing. The satellite is charting a three-dimensional map of our galaxy, pinpointing the locations, motions, and dynamics of Milky Way stars, along with additional information about many of these stars. I can’t emphasize enough how Gaia is making possible a view of the Milky Way we never had before. As regards this study, ESA said:

The analysis of the Gaia data, relying on a machine-learning algorithm, uncovered nearly 2,000 previously unidentified clusters and co-moving groups of stars up to about 3,000 light years from us – roughly 750 times the distance to Proxima Centauri, the nearest star to the sun.

The study also determined the ages for hundreds of thousands of stars, making it possible to track stellar ‘families’ and uncover their surprising arrangements.

Stellar families in Gaia’s sky. Image via ESA/Gaia/DPAC; Data: M. Kounkel & K. Covey (2019).

Kounkel added:

Around half of these stars are found in long, string-like configurations that mirror features present within their giant birth clouds.

We generally thought young stars would leave their birth sites just a few million years after they form, completely losing ties with their original family – but it seems that stars can stay close to their siblings for as long as a few billion years.

And here’s another interesting fact about these star strings, as revealed by Gaia:

The strings also appear to be oriented in particular ways with respect to our galaxy’s spiral arms – something that depends upon the ages of the stars within a string. This is especially evident for the youngest strings, comprising stars younger than 100 million years, which tend to be oriented at right angles to the spiral arm nearest to our solar system.

The astronomers suspect that the older strings of stars must have been perpendicular to the spiral arms that existed when these stars formed, which have now been reshuffled over the past billion years.

Kevin Covey, also of Western Washington University, is a study co-author. He said:

The proximity and orientation of the youngest strings to the Milky Way’s present-day spiral arms shows that older strings are an important ‘fossil record’ of our galaxy’s spiral structure.

The nature of spiral arms is still debated, with the verdict on them being stable or dynamic structures not settled yet. Studying these older strings will help us understand if the arms are mostly static, or if they move or dissipate and re-form over the course of a few hundred million years – roughly the time it takes for the sun to orbit around the galactic center a couple of times.

Further Gaia releases, including more and increasingly precise data, are planned for the coming decade, providing astronomers with the information they need to unfold the star-formation history of our galaxy. Timo Prusti, Gaia project scientist at ESA, said:

Gaia is a truly ground-breaking mission that is revealing the history of the Milky Way – and its constituent stars – like never before.

If you’ve been following Gaia, you’ll agree!

An edge-on view of stellar groups and strings in our Milky Way galaxy. Image via M. Kounkel & K. Covey (2019).

Bottom line: A new analysis of data from Gaia’s second data release has revealed that star siblings – stars born from the same cloud of gas and dust in space – stick together in long-lasting star groups moving around the center of the Milky Way. Astronomers are referring to these groups as “strings.”

Source: Untangling the Galaxy. I. Local Structure and Star Formation History of the Milky Way

Via ESA

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

Altair: Bright star of the Eagle

Rapidly rotating, hot star Altair, showing surface features and the fact that Altair’s fast rotation has flatted it. In other words, it is wider than it is tall. Image via Ming Zhao / University of Michigan

Altair is only 16.8 light-years away from Earth, making it one of our nearer stellar neighbors. At least two features of the star Altair make it distinctive.

First, Altair rotates rapidly. This star requires only about 10 hours to spin once on its axis, in contrast to 24 hours for our Earth to spin or roughly a month for our sun. In other words, this mighty star spins on its axis more rapidly than Earth! This rapid rotation tends to flatten the star a bit, much as a pizza crust flattens as it spins. Estimates are roughly that Altair’s flattening is about 14 percent. The sun also is an oblate spheroid, although its flattening is difficult to measure due to the low rotation rate.

In 2007, University of Michigan astronomers combined light from four widely separated telescopes to produce the first picture (above) showing surface details on Altair. The researchers, led by John Monnier of U-M, used optical interferometry to get this image. Read more about the study here.

Altair. Image via Wikipedia

Second, Altair stands out because it is a weak and unusual variable star with as many as 9 different rates of brightness waxings and wanings. The brightness variations are too small to measure without sensitive instruments, but likely are related to the star’s high rotation rate.

By the way, if Altair were substituted for our sun, at the distance the sun is now, life on Earth would be doomed, as Altair shines with 11 times the sun’s visible light. However, with a surface temperature of about 7550 K degrees, Altair isn’t much hotter than the sun (at 5800 K). Higher temperatures usually reveal greater mass, at least for Main Sequence stars, and Altair is thought to be in excess of 1.7 times the mass of our sun.

How to see it

Altair is the 12th brightest star, and so it is respectably bright (apparent magnitude 0.76 or 0.77), a fact that increases your likelihood of spotting it in summer or autumn skies. What’s more, Altair is flanked by two other stars, Tarazed and Alshain. When you see them, you might think of these stars as walking three abreast and arm-in-arm across the heavenly sphere.

Altair is also known as Alpha Aquilae, and it is the brightest star in the constellation Aquila the Eagle.

What’s more, stargazers know Altair as part of an entirely different and much-larger – but very recognizable – pattern. Altair is the southern apex of the Summer Triangle, which is also composed of the stars Vega and Deneb.

On the first of June, Altair rises about 90 minutes after sunset, as viewed from mid-north latitudes. By the end of September it approaches the meridian as night falls. By the end of the year, late-night observers will miss it altogether as it sets less than three hours after the sun.

Many depictions place Altair as the head or neck of an eagle with outstretched wings. The tips of the wings are formed by the Theta and Zeta stars of the constellation Aquila the Eagle, with the tail being Lambda. Once visualized, Aquila the Eagle can be seen flying eastward through the Milky Way, apparently about to devour the tiny constellation Delphinus, the Dolphin.

History and myth

The name Altair is Arabic in origin and has the same meaning as the name of the constellation Aquila in Latin; that is, they both mean simply ‘eagle.’

Altair of Aquila the Eagle, with two smaller constellations nearby. Image via Wikipedia

In classical mythology Aquila, and by extension Altair as well, was an eagle favored by Zeus. He played a part in numerous myths, including the abduction of Ganymede in which a young boy (Ganymede) is carried off to Mount Olympus on Zeus’ command to become the cupbearer to the gods. In another myth Aquila is the eagle that torments Prometheus, and is shot with a poisoned arrow by Hercules.

In India, Altair with its two flanking stars, Beta and Gamma (Tarazed and Alshain), are sometimes thought to be the celestial footprints of the god Vishnu.

Altair is separated from the similar-looking (but brighter) star Vega in the constellation Lyra by the great starlit band of the Milky Way. In Asia, this hazy band across our sky is known as the Celestial River. One story common in China, Japan and Korea a young herdsman (Altair) who falls in love with a celestial princess (Vega), who weaves the fabric of heaven. The princess became so enamored of the herdsman that she neglects her weaving duties. This acts enrages the princess’s father, the Celestial Emperor, who decrees that the herdsman must stay away from his daughter, on the opposite side of the River. The Emperor finally listened to the princess’s pleas, however, and allowed the herdsman to cross the Celestial River once per year, on the seventh day of the seventh month.

In Japan, Altair is Hikoboshi, and Vega is Orihime (or Tanabata). If it rains on the day of the festival of Tanabata, it is said to be Orihime’s tears because Hikoboshi could not navigate the treacherous waters of the Celestial River.

The position of Altair is RA: 19h 50m 47.0s, dec: +08° 52′ 06″

from EarthSky https://ift.tt/32fAPy7

Rapidly rotating, hot star Altair, showing surface features and the fact that Altair’s fast rotation has flatted it. In other words, it is wider than it is tall. Image via Ming Zhao / University of Michigan

Altair is only 16.8 light-years away from Earth, making it one of our nearer stellar neighbors. At least two features of the star Altair make it distinctive.

First, Altair rotates rapidly. This star requires only about 10 hours to spin once on its axis, in contrast to 24 hours for our Earth to spin or roughly a month for our sun. In other words, this mighty star spins on its axis more rapidly than Earth! This rapid rotation tends to flatten the star a bit, much as a pizza crust flattens as it spins. Estimates are roughly that Altair’s flattening is about 14 percent. The sun also is an oblate spheroid, although its flattening is difficult to measure due to the low rotation rate.

In 2007, University of Michigan astronomers combined light from four widely separated telescopes to produce the first picture (above) showing surface details on Altair. The researchers, led by John Monnier of U-M, used optical interferometry to get this image. Read more about the study here.

Altair. Image via Wikipedia

Second, Altair stands out because it is a weak and unusual variable star with as many as 9 different rates of brightness waxings and wanings. The brightness variations are too small to measure without sensitive instruments, but likely are related to the star’s high rotation rate.

By the way, if Altair were substituted for our sun, at the distance the sun is now, life on Earth would be doomed, as Altair shines with 11 times the sun’s visible light. However, with a surface temperature of about 7550 K degrees, Altair isn’t much hotter than the sun (at 5800 K). Higher temperatures usually reveal greater mass, at least for Main Sequence stars, and Altair is thought to be in excess of 1.7 times the mass of our sun.

How to see it

Altair is the 12th brightest star, and so it is respectably bright (apparent magnitude 0.76 or 0.77), a fact that increases your likelihood of spotting it in summer or autumn skies. What’s more, Altair is flanked by two other stars, Tarazed and Alshain. When you see them, you might think of these stars as walking three abreast and arm-in-arm across the heavenly sphere.

Altair is also known as Alpha Aquilae, and it is the brightest star in the constellation Aquila the Eagle.

What’s more, stargazers know Altair as part of an entirely different and much-larger – but very recognizable – pattern. Altair is the southern apex of the Summer Triangle, which is also composed of the stars Vega and Deneb.

On the first of June, Altair rises about 90 minutes after sunset, as viewed from mid-north latitudes. By the end of September it approaches the meridian as night falls. By the end of the year, late-night observers will miss it altogether as it sets less than three hours after the sun.

Many depictions place Altair as the head or neck of an eagle with outstretched wings. The tips of the wings are formed by the Theta and Zeta stars of the constellation Aquila the Eagle, with the tail being Lambda. Once visualized, Aquila the Eagle can be seen flying eastward through the Milky Way, apparently about to devour the tiny constellation Delphinus, the Dolphin.

History and myth

The name Altair is Arabic in origin and has the same meaning as the name of the constellation Aquila in Latin; that is, they both mean simply ‘eagle.’

Altair of Aquila the Eagle, with two smaller constellations nearby. Image via Wikipedia

In classical mythology Aquila, and by extension Altair as well, was an eagle favored by Zeus. He played a part in numerous myths, including the abduction of Ganymede in which a young boy (Ganymede) is carried off to Mount Olympus on Zeus’ command to become the cupbearer to the gods. In another myth Aquila is the eagle that torments Prometheus, and is shot with a poisoned arrow by Hercules.

In India, Altair with its two flanking stars, Beta and Gamma (Tarazed and Alshain), are sometimes thought to be the celestial footprints of the god Vishnu.

Altair is separated from the similar-looking (but brighter) star Vega in the constellation Lyra by the great starlit band of the Milky Way. In Asia, this hazy band across our sky is known as the Celestial River. One story common in China, Japan and Korea a young herdsman (Altair) who falls in love with a celestial princess (Vega), who weaves the fabric of heaven. The princess became so enamored of the herdsman that she neglects her weaving duties. This acts enrages the princess’s father, the Celestial Emperor, who decrees that the herdsman must stay away from his daughter, on the opposite side of the River. The Emperor finally listened to the princess’s pleas, however, and allowed the herdsman to cross the Celestial River once per year, on the seventh day of the seventh month.

In Japan, Altair is Hikoboshi, and Vega is Orihime (or Tanabata). If it rains on the day of the festival of Tanabata, it is said to be Orihime’s tears because Hikoboshi could not navigate the treacherous waters of the Celestial River.

The position of Altair is RA: 19h 50m 47.0s, dec: +08° 52′ 06″

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Artificial Intelligence: A Game Changer & Decisive Edge

Air Force Lt. Gen. Jack Shanahan, JOIC director, discusses how the military can address the global acceleration of AI-enabled technology.

from https://ift.tt/2ZrM58I

Air Force Lt. Gen. Jack Shanahan, JOIC director, discusses how the military can address the global acceleration of AI-enabled technology.

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Arecibo gets $19M grant to find and study NEOs

Arecibo asteroid hunters. Lead scientist Anne Virkki (center) reviews images with research scientist Flaviane Venditti (left) and postdoctoral scientist Sean Marshall (right). In the coming 4 years, under terms of the new grant, they will use the big dish at Arecibo Observatory for up to 800 hours a year to find and analyze near-Earth objects, including both asteroids and small comets. Image via UCF.

The University of Central Florida (UCF) – which manages the Arecibo Observatory in Puerto Rico on behalf of the U.S. National Science Foundation (NSF) – announced on August 26, 2019, that it has received a big NASA grant to observe and characterize near-Earth objects (NEOs) that pose a potential hazard to Earth or that could be candidates for future space missions. Total for the four-year grant: $19 million.

That’s a big investment in Arecibo, which has been using radar to analyze NEOs for some years now, since the mid-90s observing some 60 to 120 objects per year. Yet this observatory has had funding concerns in recent years, which are now, for the immediate future, solved. In a statement, UCF commented that the team of asteroid hunters at Arecibo expects:

… to gain a lot of knowledge about asteroids.

And that’s all to the good, as most will agree. In recent decades, astronomers have fully realized the potential of asteroids to strike our modern-day Earth and cause perhaps disastrous harm. More about that below. Congress made NEOs a priority when it directed NASA in 2005 to seek out and characterize at least 90 percent of near-Earth objects larger than 140 meters (459 feet) by the year 2020. This new grant – a four-year, $19M award – comes on the heels of a 4-year, 12.3M grant, announced earlier this month, for emergency supplemental funds for upgrades and repairs to the big Arecibo radio dish and surrounding site, needed especially in recent years as multiple hurricanes have swept across the Caribbean, including Hurricanes Irma and Maria in 2017.

The combination of the two grants puts Arecibo on very strong footing, for now.

It’s interesting in part because Arecibo was the world’s largest single-aperture telescope from its completion in 1963 until July 2016 … but no more. That honor now goes to China’s Five hundred meter Aperture Spherical Telescope (FAST). Prior to FAST, Arecibo was described as uniquely powerful at finding and analyzing NEOs. That may still be true, and it’s certainly the case that the big dish at Arecibo – built into a natural depression in the landscape of this Caribbean island – is a powerful tool for professional research not just in radar studies of NEOs but also for radio astronomy and atmospheric studies.

A wide view of the Arecibo radio dish. The main collecting dish is 1,000 feet (305 meters) in diameter, constructed inside the depression left by a karst sinkhole. Image via Arecibo Observatory.

UCF said in a statement:

The observatory is home to the most powerful and most sensitive planetary radar system in the world, which means it is also a unique tool available to analyze NEOs, such as asteroids and comets. The knowledge helps NASA determine which objects pose significant risks and when and what to do to mitigate them. NASA officials can also use the information to determine which objects are the most viable for science missions – landing on an asteroid is not equally easy for all of them. Information the observatory provided about asteroid Bennu, for example, is one of the factors that led NASA to select the OSIRIS-REx mission for funding.

The award also includes money to support STEM education among high school students in Puerto Rico, [bringing] together 30 local high-school students per semester once a week for 16 classes to learn about science and research at the observatory.

The Arecibo planetary radar program’s principal scientist is Anne Virkki (follow her at @annevirkki on Twitter). She explained how radar studies can advance human knowledge of asteroids:

The S-band planetary radar system … at Arecibo Observatory is the most sensitive planetary radar system in the world. This is why Arecibo is such an amazing tool for our work. Our radar astrometry and characterization are critical for identifying objects that are truly hazardous to Earth and for the planning of mitigation efforts. We can use our system to constrain the size, shape, mass, spin state, composition, binarity, trajectory, and gravitational and surface environments of NEOs and this will help NASA to determine potential targets for future missions.

This animation is built from Arecibo radar images of near-Earth asteroid 3200 Phaethon, acquired from December 15 through 19, 2017. Read more.

When I started writing about astronomy in the 1970s, some astronomers scoffed at the notion that our modern-day Earth might be struck by an asteroid. Of course, scientists knew Earth had been struck many times in the past. Although most meteor craters on Earth have been worn away by wind and weather, large meteor craters do still pockmark Earth’s surface in some places, for example, Meteor Crater near Winslow, Arizona. These craters are visible signs that large asteroids can and did bombard our planet, but those bombardments were, for the most part, relegated solely to the distant past by most astronomers until relatively recently.

Several things changed to alter that view. For one thing, an event in living memory – the Tunguska event of 1908, which had taken place in a remote part of Siberia and remained mysterious for many years – came to be widely accepted as likely being caused by a small comet or stony asteroid. More importantly, technology changed, improving to the point where astronomers could discover vastly more asteroids than before. A few thousand asteroids were known and named in the 1970s. Now hundreds of thousands of asteroids are known, and, indeed, some have orbits that bring them near Earth. These are the near-Earth objects (NEOs) that NASA wants to hunt down and track with Arecibo, and, ultimately, to visit.

The NEOs are a blessing and a curse. They contain raw materials that humanity may someday be able to mine. But, although astronomers do know for certain that no large world-destroying asteroid is on a collision course with Earth for the foreseeable future, we are less certain about the smaller asteroids, the ones that could, say, destroy a city. In recent years, astronomers have begun to speak of Earth in the cosmic shooting gallery. The Earth is the target in this way of looking at things, and asteroids are the bullets.

Small asteroids sweep near Earth all the time. It’s not unusual for a small asteroid to sweep closer to us than the moon. Scientists estimate that several dozen asteroids in the 6– to 12-meter (20- to 39-feet) size range fly by Earth at a distance closer than the moon every year. Only a fraction of these are detected.

NASA wants to detect more of those close-passing asteroids. It wants to learn to travel to asteroids and mitigate the potential for a collision. That’s why it just awarded this large grant to Arecibo. Good luck, asteroid hunters!

The beam-steering mechanism and some antennas at world-famous Arecibo Observatory in Puerto Rico. Ferdinand Arroyo, from Sociedad de Astronomía del Caribe (Astronomical Society of the Caribbean) took this beautiful photo in 2014. Read more about this image.

Bottom line: Arecibo Observatory has just received a 4-year, $19 million grant from NASA to find and study near-Earth objects (NEOs).

Via UCF

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Arecibo asteroid hunters. Lead scientist Anne Virkki (center) reviews images with research scientist Flaviane Venditti (left) and postdoctoral scientist Sean Marshall (right). In the coming 4 years, under terms of the new grant, they will use the big dish at Arecibo Observatory for up to 800 hours a year to find and analyze near-Earth objects, including both asteroids and small comets. Image via UCF.

The University of Central Florida (UCF) – which manages the Arecibo Observatory in Puerto Rico on behalf of the U.S. National Science Foundation (NSF) – announced on August 26, 2019, that it has received a big NASA grant to observe and characterize near-Earth objects (NEOs) that pose a potential hazard to Earth or that could be candidates for future space missions. Total for the four-year grant: $19 million.

That’s a big investment in Arecibo, which has been using radar to analyze NEOs for some years now, since the mid-90s observing some 60 to 120 objects per year. Yet this observatory has had funding concerns in recent years, which are now, for the immediate future, solved. In a statement, UCF commented that the team of asteroid hunters at Arecibo expects:

… to gain a lot of knowledge about asteroids.

And that’s all to the good, as most will agree. In recent decades, astronomers have fully realized the potential of asteroids to strike our modern-day Earth and cause perhaps disastrous harm. More about that below. Congress made NEOs a priority when it directed NASA in 2005 to seek out and characterize at least 90 percent of near-Earth objects larger than 140 meters (459 feet) by the year 2020. This new grant – a four-year, $19M award – comes on the heels of a 4-year, 12.3M grant, announced earlier this month, for emergency supplemental funds for upgrades and repairs to the big Arecibo radio dish and surrounding site, needed especially in recent years as multiple hurricanes have swept across the Caribbean, including Hurricanes Irma and Maria in 2017.

The combination of the two grants puts Arecibo on very strong footing, for now.

It’s interesting in part because Arecibo was the world’s largest single-aperture telescope from its completion in 1963 until July 2016 … but no more. That honor now goes to China’s Five hundred meter Aperture Spherical Telescope (FAST). Prior to FAST, Arecibo was described as uniquely powerful at finding and analyzing NEOs. That may still be true, and it’s certainly the case that the big dish at Arecibo – built into a natural depression in the landscape of this Caribbean island – is a powerful tool for professional research not just in radar studies of NEOs but also for radio astronomy and atmospheric studies.

A wide view of the Arecibo radio dish. The main collecting dish is 1,000 feet (305 meters) in diameter, constructed inside the depression left by a karst sinkhole. Image via Arecibo Observatory.

UCF said in a statement:

The observatory is home to the most powerful and most sensitive planetary radar system in the world, which means it is also a unique tool available to analyze NEOs, such as asteroids and comets. The knowledge helps NASA determine which objects pose significant risks and when and what to do to mitigate them. NASA officials can also use the information to determine which objects are the most viable for science missions – landing on an asteroid is not equally easy for all of them. Information the observatory provided about asteroid Bennu, for example, is one of the factors that led NASA to select the OSIRIS-REx mission for funding.

The award also includes money to support STEM education among high school students in Puerto Rico, [bringing] together 30 local high-school students per semester once a week for 16 classes to learn about science and research at the observatory.

The Arecibo planetary radar program’s principal scientist is Anne Virkki (follow her at @annevirkki on Twitter). She explained how radar studies can advance human knowledge of asteroids:

The S-band planetary radar system … at Arecibo Observatory is the most sensitive planetary radar system in the world. This is why Arecibo is such an amazing tool for our work. Our radar astrometry and characterization are critical for identifying objects that are truly hazardous to Earth and for the planning of mitigation efforts. We can use our system to constrain the size, shape, mass, spin state, composition, binarity, trajectory, and gravitational and surface environments of NEOs and this will help NASA to determine potential targets for future missions.

This animation is built from Arecibo radar images of near-Earth asteroid 3200 Phaethon, acquired from December 15 through 19, 2017. Read more.

When I started writing about astronomy in the 1970s, some astronomers scoffed at the notion that our modern-day Earth might be struck by an asteroid. Of course, scientists knew Earth had been struck many times in the past. Although most meteor craters on Earth have been worn away by wind and weather, large meteor craters do still pockmark Earth’s surface in some places, for example, Meteor Crater near Winslow, Arizona. These craters are visible signs that large asteroids can and did bombard our planet, but those bombardments were, for the most part, relegated solely to the distant past by most astronomers until relatively recently.

Several things changed to alter that view. For one thing, an event in living memory – the Tunguska event of 1908, which had taken place in a remote part of Siberia and remained mysterious for many years – came to be widely accepted as likely being caused by a small comet or stony asteroid. More importantly, technology changed, improving to the point where astronomers could discover vastly more asteroids than before. A few thousand asteroids were known and named in the 1970s. Now hundreds of thousands of asteroids are known, and, indeed, some have orbits that bring them near Earth. These are the near-Earth objects (NEOs) that NASA wants to hunt down and track with Arecibo, and, ultimately, to visit.

The NEOs are a blessing and a curse. They contain raw materials that humanity may someday be able to mine. But, although astronomers do know for certain that no large world-destroying asteroid is on a collision course with Earth for the foreseeable future, we are less certain about the smaller asteroids, the ones that could, say, destroy a city. In recent years, astronomers have begun to speak of Earth in the cosmic shooting gallery. The Earth is the target in this way of looking at things, and asteroids are the bullets.

Small asteroids sweep near Earth all the time. It’s not unusual for a small asteroid to sweep closer to us than the moon. Scientists estimate that several dozen asteroids in the 6– to 12-meter (20- to 39-feet) size range fly by Earth at a distance closer than the moon every year. Only a fraction of these are detected.

NASA wants to detect more of those close-passing asteroids. It wants to learn to travel to asteroids and mitigate the potential for a collision. That’s why it just awarded this large grant to Arecibo. Good luck, asteroid hunters!

The beam-steering mechanism and some antennas at world-famous Arecibo Observatory in Puerto Rico. Ferdinand Arroyo, from Sociedad de Astronomía del Caribe (Astronomical Society of the Caribbean) took this beautiful photo in 2014. Read more about this image.

Bottom line: Arecibo Observatory has just received a 4-year, $19 million grant from NASA to find and study near-Earth objects (NEOs).

Via UCF

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Amazon fires viewed from ISS

August 24, 2019 image from the International Space Station shows multiple fires burning in the Amazon rainforest. As astronaut Luca Paritano, who acquired the images from orbit 250 miles (400 km) above Earth, tweeted: #noplanetB.

European Space Agency astronaut Luca Parmitano took this image on August 24, 2019 from his vantage point in the International Space Station. He tweeted this and other images of the fires, captioning them:

The smoke, visible for thousands of kilometers, of tens of human-caused fires in the Amazon forest.

The smoke, visible for thousands of kilometres, of tens of human-caused fires in the Amazon forest. #noplanetB #MissionBeyond pic.twitter.com/SyoydfJo39

— Luca Parmitano (@astro_luca) August 26, 2019

ESA wrote of the images on August 27:

The Amazon basin is home to millions of plants and animals and many indigenous people. It also produces around 20% of Earth’s oxygen, for which it is sometimes referred to as ‘the lungs of the world’. The Amazon rainforest covers large parts of Brazil, as well as parts of Peru, Bolivia, Paraguay and Argentina, all of which have been affected.

While fires rage in the rainforest, strong winds have carried smoke plumes thousands of kilometres across land and sea, causing a black out in São Paulo, Brazil, some 2,500 kilometers [1,500 miles] away. Data from Copernicus Atmosphere Monitoring System (CAMS) shows that smoke has even travelled as far as the Atlantic coast.

Fires are common during the dry season, which runs from July to October. But this year is unlike any other.

Copernicus Sentinel-3 data has helped to detect almost 4,000 fires in August 2019 alone, compared to only 1110 fires in the same period last year.

This year’s unprecedented blazes are four times the normal amount and are likely due to legal and illegal deforestation for agricultural purposes.

Rising global temperatures are also thought to make the region more susceptible to fire.

Read more about the fires and how satellites are observing them in this article from ESA.

The scale of the Amazon fires can be seen in this map, which is via AFP/ Metro.co.uk.

Bottom line: Image acquired from ISS showing fires in the Amazon on August 24, 2019.

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August 24, 2019 image from the International Space Station shows multiple fires burning in the Amazon rainforest. As astronaut Luca Paritano, who acquired the images from orbit 250 miles (400 km) above Earth, tweeted: #noplanetB.

European Space Agency astronaut Luca Parmitano took this image on August 24, 2019 from his vantage point in the International Space Station. He tweeted this and other images of the fires, captioning them:

The smoke, visible for thousands of kilometers, of tens of human-caused fires in the Amazon forest.

The smoke, visible for thousands of kilometres, of tens of human-caused fires in the Amazon forest. #noplanetB #MissionBeyond pic.twitter.com/SyoydfJo39

— Luca Parmitano (@astro_luca) August 26, 2019

ESA wrote of the images on August 27:

The Amazon basin is home to millions of plants and animals and many indigenous people. It also produces around 20% of Earth’s oxygen, for which it is sometimes referred to as ‘the lungs of the world’. The Amazon rainforest covers large parts of Brazil, as well as parts of Peru, Bolivia, Paraguay and Argentina, all of which have been affected.

While fires rage in the rainforest, strong winds have carried smoke plumes thousands of kilometres across land and sea, causing a black out in São Paulo, Brazil, some 2,500 kilometers [1,500 miles] away. Data from Copernicus Atmosphere Monitoring System (CAMS) shows that smoke has even travelled as far as the Atlantic coast.

Fires are common during the dry season, which runs from July to October. But this year is unlike any other.

Copernicus Sentinel-3 data has helped to detect almost 4,000 fires in August 2019 alone, compared to only 1110 fires in the same period last year.

This year’s unprecedented blazes are four times the normal amount and are likely due to legal and illegal deforestation for agricultural purposes.

Rising global temperatures are also thought to make the region more susceptible to fire.

Read more about the fires and how satellites are observing them in this article from ESA.

The scale of the Amazon fires can be seen in this map, which is via AFP/ Metro.co.uk.

Bottom line: Image acquired from ISS showing fires in the Amazon on August 24, 2019.

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