Gemini? Here’s your constellation

Is Gemini “your” constellation, and you want to know how to see it in the night sky? This post can help. It offers several ways to find the constellation Gemini, plus gives you some of the sky lore and mythology associated with this constellation. Follow the links below for mini-lessons on the constellation Gemini:

When and how can I see the constellation Gemini in the night sky?

Find Gemini from the constellation Orion.

Use the Big Dipper to find Gemini.

Use the moon to find Gemini.

Mythology and lore of the heavenly Twins.

Here’s one way to see the constellation Gemini. The two bright stars Castor and Pollux each mark a starry eye of a Twin. If you have binoculars and a dark sky, be sure to check out Gemini’s beautiful star cluster, Messier 35, or M35, in western Gemini near the Taurus border. See it, at the foot of Castor?

The fuzzy cluster at the lower right of this photo is M35 in Gemini. Image via Wikimedia Commons

When and how can I see the constellation Gemini in the night sky? You have lots of months during the year to observe Gemini, which is one of the brighter constellations of the Zodiac. The constellation Gemini lights up the early evening sky from January until May, though it’ll set in the west two hours earlier with each passing month. As seen from mid-northern latitudes, for example, Gemini stands upright over the western horizon around 5 a.m. local time in early February, 3 a.m. in early March, 1 a.m. (2 a.m. daylight saving time) in early April and 11 p.m. (midnight daylight saving time) in early May.

January and February present a grand time for observing the constellation Gemini because it is well up in the east at nightfall and stays out for most of the night. Gemini climbs highest in the sky around 10 p.m. local time in early February and 9 p.m. in late February. That’s local time, the time on your clock, no matter where you live around the globe.

Gemini stays in view in the evening sky on through to May. By late May and June, Gemini is found low in the west-northwest corner of the sky at nightfall, and Gemini’s two brightest stars – Castor and Pollux – fade into the sunset by around the June 21 summer solstice.

Gemini is best identified by its two brightest stars, Castor and Pollux. These two are noticeable for being bright and close together on the sky’s dome. Like brothers!

Castor is six stars in one

Pollux is the brighter of two Twin stars

By the way, Gemini and nighttime’s brightest star, Sirius, reach the crest of their travels for the night at roughly the same time. At middle latitudes in the Northern Hemisphere, we see Gemini’s brightest stars, Castor and Pollux nearly overhead while Sirius sparkles quite low in our southern sky. South of the equator, it’s the opposite: Sirius shines way up high while Gemini sits low in the northern sky.

The sun annually passes in front of the constellation Gemini the Twins from about June 21 until July 20. To remember these dates, keep in mind that the sun enters Gemini just after the June solstice and stays within Gemini for the following month. Gemini can’t be seen in late spring and early summer in the Northern Hemisphere – or late autumn and early winter in the Southern Hemisphere – because this is when the Heavenly Twins are lost in the glare of the sun.

Drawn an imaginary line from Rigel through Betelgeuse to star-hop to Castor and Pollux

Find Gemini from the constellation Orion. If you pick out any noticeable sky pattern in the February night sky, that pattern has a good chance of being the constellation Orion the Hunter. On these February evenings, from the Northern Hemisphere, Orion is high in the south.

Orion noticeable for its Belt stars, a short, straight row of three medium-bright stars. Look below Orion’s Belt for the very bright star Rigel. See it? Now look above Orion’s Belt for the star Betelgeuse. See that? You can draw an imaginary line from Rigel through Betelgeuse to locate Castor and Pollux. Remember, you’ll be looking for two bright stars that are noticeably close together.

Draw an imaginary line diagonally through the Big Dipper bowl to locate Castor and Pollux

Use the Big Dipper to find Gemini. This asterism – not a true constellation, but just a very clear dipper-shaped pattern of stars – is always located generally northward on the sky’s dome. Draw an imaginary line diagonally through the bowl of the Big Dipper, from the star Megrez through the star Merak. You are going in the direction opposite of the Big Dipper handle. This line will point to Castor and Pollux.

Big and Little Dippers: Noticeable in the northern sky

Use the moon to find Gemini. As the moon swings full circle through the constellations of the Zodiac, it passes through Gemini for a few days each month. Look on the sky chart above to see the ecliptic as a dotted red line crossing Gemini. The ecliptic marks the sun’s path on which the sun goes eastward (from right to left) in between the two bright Gemini stars, Castor and Pollux, and the brilliant star Procyon of Canis Minor the Lesser Dog. Whereas the sun passes eastward through Gemini for about one month a year, the moon goes eastward through Gemini for a few days each month.

Because the moon stays within plus or minus 5^o (10 moon diameters) of the ecliptic – the sun’s path through the stars – the moon travels to the south of Castor and Pollux, and to the north of Procyon as it promenades across Gemini. In cycles of 18.6 years, the moon reaches its farthest point north of the ecliptic in Taurus and just misses occulting – covering over – the star Pollux. In ancient times, when Pollux was a little closer to the ecliptic, the moon used to occult – cover over – this star in centuries B.C.

Image credit: Wikipedia

Myth of the heavenly Twins. The scroll of the lore-laden heavens represents the meeting place of mortality and immortality, of where ancestry and posterity live together. Certainly, the Greek myth of Castor and Pollux explores the inherit duality of life – of mortality and immortality forever intertwined and perpetually in conflict.

Castor and Pollux were the sons of the god Zeus and their mortal mother Leda. The offspring were a mix of the base and divine, with Castor being the mortal brother and Pollux immortal. The two brothers well portray the dilemma of the human condition, the story repeating itself over the generations. Castor and Pollux were joyfully united in spirit yet sorrowfully divided by circumstance.

When Castor was slain in battle, Pollux was inconsolable in grief, begging Zeus to relieve him of the bonds of immortality. Pollux chose death, so that he could join his brother Castor in the great beyond. To this day, Pollux and Castor stand reunited in the heavens, a tribute to the redemptive power of brotherly love.

Bottom line: Want to find the constellation Gemini in the night sky. Winter and spring provide a good time to look. This constellation is noticeable for two bright stars that are close together on the sky’s dome. In the mythology of the night sky, these two stars represent twin brothers.

Taurus? Here’s your constellation

Gemini? Here’s your constellation

Cancer? Here’s your constellation

Leo? Here’s your constellation

Virgo? Here’s your constellation

Libra? Here’s your constellation

Scorpius? Here’s your contellation

Sagittarius? Here’s your constellation

Capricornus? Here’s your constellation

Aquarius? Here’s your constellation

Pisces? Here’s your constellation

Aries? Here’s your constellation

Birthday late November to early December? Here’s your constellation

from EarthSky http://ift.tt/1zd7L5M

Is Gemini “your” constellation, and you want to know how to see it in the night sky? This post can help. It offers several ways to find the constellation Gemini, plus gives you some of the sky lore and mythology associated with this constellation. Follow the links below for mini-lessons on the constellation Gemini:

When and how can I see the constellation Gemini in the night sky?

Find Gemini from the constellation Orion.

Use the Big Dipper to find Gemini.

Use the moon to find Gemini.

Mythology and lore of the heavenly Twins.

Here’s one way to see the constellation Gemini. The two bright stars Castor and Pollux each mark a starry eye of a Twin. If you have binoculars and a dark sky, be sure to check out Gemini’s beautiful star cluster, Messier 35, or M35, in western Gemini near the Taurus border. See it, at the foot of Castor?

The fuzzy cluster at the lower right of this photo is M35 in Gemini. Image via Wikimedia Commons

When and how can I see the constellation Gemini in the night sky? You have lots of months during the year to observe Gemini, which is one of the brighter constellations of the Zodiac. The constellation Gemini lights up the early evening sky from January until May, though it’ll set in the west two hours earlier with each passing month. As seen from mid-northern latitudes, for example, Gemini stands upright over the western horizon around 5 a.m. local time in early February, 3 a.m. in early March, 1 a.m. (2 a.m. daylight saving time) in early April and 11 p.m. (midnight daylight saving time) in early May.

January and February present a grand time for observing the constellation Gemini because it is well up in the east at nightfall and stays out for most of the night. Gemini climbs highest in the sky around 10 p.m. local time in early February and 9 p.m. in late February. That’s local time, the time on your clock, no matter where you live around the globe.

Gemini stays in view in the evening sky on through to May. By late May and June, Gemini is found low in the west-northwest corner of the sky at nightfall, and Gemini’s two brightest stars – Castor and Pollux – fade into the sunset by around the June 21 summer solstice.

Gemini is best identified by its two brightest stars, Castor and Pollux. These two are noticeable for being bright and close together on the sky’s dome. Like brothers!

Castor is six stars in one

Pollux is the brighter of two Twin stars

By the way, Gemini and nighttime’s brightest star, Sirius, reach the crest of their travels for the night at roughly the same time. At middle latitudes in the Northern Hemisphere, we see Gemini’s brightest stars, Castor and Pollux nearly overhead while Sirius sparkles quite low in our southern sky. South of the equator, it’s the opposite: Sirius shines way up high while Gemini sits low in the northern sky.

The sun annually passes in front of the constellation Gemini the Twins from about June 21 until July 20. To remember these dates, keep in mind that the sun enters Gemini just after the June solstice and stays within Gemini for the following month. Gemini can’t be seen in late spring and early summer in the Northern Hemisphere – or late autumn and early winter in the Southern Hemisphere – because this is when the Heavenly Twins are lost in the glare of the sun.

Drawn an imaginary line from Rigel through Betelgeuse to star-hop to Castor and Pollux

Find Gemini from the constellation Orion. If you pick out any noticeable sky pattern in the February night sky, that pattern has a good chance of being the constellation Orion the Hunter. On these February evenings, from the Northern Hemisphere, Orion is high in the south.

Orion noticeable for its Belt stars, a short, straight row of three medium-bright stars. Look below Orion’s Belt for the very bright star Rigel. See it? Now look above Orion’s Belt for the star Betelgeuse. See that? You can draw an imaginary line from Rigel through Betelgeuse to locate Castor and Pollux. Remember, you’ll be looking for two bright stars that are noticeably close together.

Draw an imaginary line diagonally through the Big Dipper bowl to locate Castor and Pollux

Use the Big Dipper to find Gemini. This asterism – not a true constellation, but just a very clear dipper-shaped pattern of stars – is always located generally northward on the sky’s dome. Draw an imaginary line diagonally through the bowl of the Big Dipper, from the star Megrez through the star Merak. You are going in the direction opposite of the Big Dipper handle. This line will point to Castor and Pollux.

Big and Little Dippers: Noticeable in the northern sky

Use the moon to find Gemini. As the moon swings full circle through the constellations of the Zodiac, it passes through Gemini for a few days each month. Look on the sky chart above to see the ecliptic as a dotted red line crossing Gemini. The ecliptic marks the sun’s path on which the sun goes eastward (from right to left) in between the two bright Gemini stars, Castor and Pollux, and the brilliant star Procyon of Canis Minor the Lesser Dog. Whereas the sun passes eastward through Gemini for about one month a year, the moon goes eastward through Gemini for a few days each month.

Because the moon stays within plus or minus 5^o (10 moon diameters) of the ecliptic – the sun’s path through the stars – the moon travels to the south of Castor and Pollux, and to the north of Procyon as it promenades across Gemini. In cycles of 18.6 years, the moon reaches its farthest point north of the ecliptic in Taurus and just misses occulting – covering over – the star Pollux. In ancient times, when Pollux was a little closer to the ecliptic, the moon used to occult – cover over – this star in centuries B.C.

Image credit: Wikipedia

Myth of the heavenly Twins. The scroll of the lore-laden heavens represents the meeting place of mortality and immortality, of where ancestry and posterity live together. Certainly, the Greek myth of Castor and Pollux explores the inherit duality of life – of mortality and immortality forever intertwined and perpetually in conflict.

Castor and Pollux were the sons of the god Zeus and their mortal mother Leda. The offspring were a mix of the base and divine, with Castor being the mortal brother and Pollux immortal. The two brothers well portray the dilemma of the human condition, the story repeating itself over the generations. Castor and Pollux were joyfully united in spirit yet sorrowfully divided by circumstance.

When Castor was slain in battle, Pollux was inconsolable in grief, begging Zeus to relieve him of the bonds of immortality. Pollux chose death, so that he could join his brother Castor in the great beyond. To this day, Pollux and Castor stand reunited in the heavens, a tribute to the redemptive power of brotherly love.

Bottom line: Want to find the constellation Gemini in the night sky. Winter and spring provide a good time to look. This constellation is noticeable for two bright stars that are close together on the sky’s dome. In the mythology of the night sky, these two stars represent twin brothers.

Taurus? Here’s your constellation

Gemini? Here’s your constellation

Cancer? Here’s your constellation

Leo? Here’s your constellation

Virgo? Here’s your constellation

Libra? Here’s your constellation

Scorpius? Here’s your contellation

Sagittarius? Here’s your constellation

Capricornus? Here’s your constellation

Aquarius? Here’s your constellation

Pisces? Here’s your constellation

Aries? Here’s your constellation

Birthday late November to early December? Here’s your constellation

from EarthSky http://ift.tt/1zd7L5M

When Should Animals Be Used for Research or Industry Testing?

Source: DoNow Science

Tags: animal rights, animal testing, animal welfare, animals, apes, chimpanzees, ethics, featured, full-image





from QUEST http://ift.tt/1Ap4xjQ

Source: DoNow Science

Tags: animal rights, animal testing, animal welfare, animals, apes, chimpanzees, ethics, featured, full-image





from QUEST http://ift.tt/1Ap4xjQ

What are circumpolar stars?

Circumpolar stars always reside above the horizon, and for that reason, never rise or set. All the stars at the Earth’s North and South Poles are circumpolar, whereas no star is circumpolar at the Earth’s equator.

Anyplace else has some circumpolar stars, and some stars that rise and set daily. The closer you are to either the North or South Pole, the greater the circle of circumpolar stars, and the closer you are to the equator, the smaller.

From the Northern Hemisphere, all the stars in the sky go full circle around the north celestial pole once a day – or more precisely, go full circle every 23 hours and 56 minutes. And from the Southern hemisphere, all the stars in the sky go full circle around the south celestial pole in 23 hours and 56 minutes.

The Big Dipper and the W-shaped constellation Cassiopeia circle around Polaris, the North Star, in a period of 23 hours and 56 minutes. The Big Dipper is circumpolar at 41^o N. latitude, and all latitudes farther north.

We in the Northern Hemisphere are particularly lucky to have Polaris, a moderately-bright star, closely marking the north celestial pole – the point in the starry sky that’s at zenith (directly overhead) at the Earth’s North Pole.

At the equator (0^o latitude) the star Polaris – the stellar hub – sits right on the northern horizon, so no star can be circumpolar at the Earth’s equator. But at the North Pole (90^o) Polaris shines at zenith (directly overhead), so from the North Pole every star in the sky stays above the horizon all day long every day of the year.

The circle of circumpolar stars in your sky is determined by your latitude. For instance, at 30^o North latitude, the circle of stars within a radius of 30^o from Polaris is circumpolar. In the same vein, at 45^o or 60^o N. latitude, the circle of stars within 45^o or 60^o, respectively, of Polaris would be circumpolar. Finally, at the North Pole, the circle of stars all the way to the horizon is circumpolar.

View larger. The stars revolve around the North Star, which serves as the center of the great celestial clock. Star trails produced by long time exposure photograph.

At 41^o North Latitude (the latitude of New York City), and all latitudes farther north, the famous Big Dipper asterism is circumpolar. That’s because the southernmost star of the Big Dipper, Alkaid – the star marking the end of the Big Dipper handle – is 41^o south of the north celestial pole (or 49^o north of the celestial equator).

If you’re in the northern U.S., Canada or at a similar latitude, the Big Dipper is circumpolar for you – always above the horizon. These images show the Dipper’s location at around midnight in these seasons. Just remember “spring up and fall down” for the Dipper’s appearance in our northern sky. It ascends in the northeast on spring evenings, and descends in the northwest on fall evenings. Image via burro.astr.cwru.edu

In short, every star rises and sets at the Earth’s equator, but no star rises or sets at the Earth’s North and South Poles.

from EarthSky http://ift.tt/1AoPRBl

Circumpolar stars always reside above the horizon, and for that reason, never rise or set. All the stars at the Earth’s North and South Poles are circumpolar, whereas no star is circumpolar at the Earth’s equator.

Anyplace else has some circumpolar stars, and some stars that rise and set daily. The closer you are to either the North or South Pole, the greater the circle of circumpolar stars, and the closer you are to the equator, the smaller.

From the Northern Hemisphere, all the stars in the sky go full circle around the north celestial pole once a day – or more precisely, go full circle every 23 hours and 56 minutes. And from the Southern hemisphere, all the stars in the sky go full circle around the south celestial pole in 23 hours and 56 minutes.

The Big Dipper and the W-shaped constellation Cassiopeia circle around Polaris, the North Star, in a period of 23 hours and 56 minutes. The Big Dipper is circumpolar at 41^o N. latitude, and all latitudes farther north.

We in the Northern Hemisphere are particularly lucky to have Polaris, a moderately-bright star, closely marking the north celestial pole – the point in the starry sky that’s at zenith (directly overhead) at the Earth’s North Pole.

At the equator (0^o latitude) the star Polaris – the stellar hub – sits right on the northern horizon, so no star can be circumpolar at the Earth’s equator. But at the North Pole (90^o) Polaris shines at zenith (directly overhead), so from the North Pole every star in the sky stays above the horizon all day long every day of the year.

The circle of circumpolar stars in your sky is determined by your latitude. For instance, at 30^o North latitude, the circle of stars within a radius of 30^o from Polaris is circumpolar. In the same vein, at 45^o or 60^o N. latitude, the circle of stars within 45^o or 60^o, respectively, of Polaris would be circumpolar. Finally, at the North Pole, the circle of stars all the way to the horizon is circumpolar.

View larger. The stars revolve around the North Star, which serves as the center of the great celestial clock. Star trails produced by long time exposure photograph.

At 41^o North Latitude (the latitude of New York City), and all latitudes farther north, the famous Big Dipper asterism is circumpolar. That’s because the southernmost star of the Big Dipper, Alkaid – the star marking the end of the Big Dipper handle – is 41^o south of the north celestial pole (or 49^o north of the celestial equator).

If you’re in the northern U.S., Canada or at a similar latitude, the Big Dipper is circumpolar for you – always above the horizon. These images show the Dipper’s location at around midnight in these seasons. Just remember “spring up and fall down” for the Dipper’s appearance in our northern sky. It ascends in the northeast on spring evenings, and descends in the northwest on fall evenings. Image via burro.astr.cwru.edu

In short, every star rises and sets at the Earth’s equator, but no star rises or sets at the Earth’s North and South Poles.

from EarthSky http://ift.tt/1AoPRBl

Nos Aries location for IXV splashdown

The Google map widget showing where the recovery ship Nos Aries will be located for IXV splashdown, expected about 104 minutes after lift off on 11 February. The ship's tracking antenna will also be the first to receive the wingless spaceplane's call to earth after it emerges from the reentry blackout. Details via 100 minutes of crucial teamwork .

from Rocket Science » Rocket Science http://ift.tt/1yBvjjj

v

The Google map widget showing where the recovery ship Nos Aries will be located for IXV splashdown, expected about 104 minutes after lift off on 11 February. The ship's tracking antenna will also be the first to receive the wingless spaceplane's call to earth after it emerges from the reentry blackout. Details via 100 minutes of crucial teamwork .

from Rocket Science » Rocket Science http://ift.tt/1yBvjjj

v

Republicans have one option to eliminate EPA carbon regulations

The US Environmental Protection Agency is in the process of creating regulations on carbon pollution from power plants, and Republicans in Congress hate the idea. Surprisingly, a majority of Republican voters support these regulations, with Tea Party members being the only exception.

Results of a recent Yale/George Mason Universities poll of American political conservatives.

Nevertheless, Republicans in Congress badly want to kill those regulations. However, they’re pursuing the avenues with the lowest chances of achieving that goal.

It’s important to remember that the EPA carbon pollution regulations are legally mandated. In 2007, the US Supreme Court ruled that if it determined that carbon pollution poses a threat to public health or welfare, the EPA would be required to regulate emissions of that pollution under the Clean Air Act. In 2009, the EPA issued its endangerment finding, citing several comprehensive climate science reports, correctly concluding that carbon pollution poses a threat to public health and welfare and must therefore be regulated.

So while some Republicans in Congress have called the proposed carbon pollution regulations an “executive overreach,” in reality the EPA is simply implementing the law of the land.

Doomed GOP Challenges

Senate majority leader Mitch McConnell (R-KY) introduced legislation last year to block the EPA regulations. But even if that bill could make it through Congress, it would face a certain veto by President Obama.

There’s another effort to challenge the EPA regulations in court. These recently made headlines because they involve Laurence Tribe, for whom Obama was a research assistant at Harvard. Tribe has argued that the EPA regulations violate Section 111(d) of the Clean Air Act, and the DC court of appeals has just agreed to hear the arguments.

However, the chances of success for this legal challenge are extremely slim. NRDC attorney Benjamin Longstreth told me,

I would not read anything into the Court’s decision to schedule argument. The case has not even been briefed yet (that’s ongoing) so the decision to schedule argument doesn’t reflect anyone’s view of the merits of the case (the judges who are going to decide the case won’t even have the briefs yet) ... But it is important to remember that these cases are fatally premature (an issue that Tribe doesn’t address). You can only challenge a final agency decision. Here the petitioners seek to challenge a proposed rule.

Tribe’s main argument lies in the claim that Section 111(d) of the Clean Air Act says that the EPA can’t regulate an air pollutant if it’s already regulating another pollutant from the same source. The EPA already regulates mercury emissions from power plants. However, this is an inaccurate reading of both the letter and intent of the law. Moreover, as Longstreth and his colleague David Doniger have explained, the Supreme Court has effectively already ruled on this issue (emphasis added).

This is how the Supreme Court interpreted the provision in American Electric Power v. Connecticut . There the Court held that plaintiffs could not bring a federal tort action against major electric power companies for their emissions of carbon dioxide, because the Clean Air Act authorized EPA to regulate power plants’ carbon dioxide pollution under Section 111(d).

An Easy Alternative Path

While efforts to block or challenge the legality of the EPA carbon pollution regulations are all but doomed to failure, there is one way that Republicans in Congress could get rid of those regulations at any time. President Obama told Congress that if it didn’t act to address the threat of climate change, he would. But he and congressional Democrats would rather take action via a free market solution.

With support from just a few of its Republican members, Congress could pass climate legislation that would replace the EPA regulations with a carbon pricing mechanism. Efforts were previously made (but failed by a slim margin) to implement a carbon cap and trade system. More recently, a revenue-neutral carbon tax has become the favored policy, especially among conservatives.

Click here to read the rest

from Skeptical Science http://ift.tt/1zb4q9H

The US Environmental Protection Agency is in the process of creating regulations on carbon pollution from power plants, and Republicans in Congress hate the idea. Surprisingly, a majority of Republican voters support these regulations, with Tea Party members being the only exception.

Results of a recent Yale/George Mason Universities poll of American political conservatives.

Nevertheless, Republicans in Congress badly want to kill those regulations. However, they’re pursuing the avenues with the lowest chances of achieving that goal.

It’s important to remember that the EPA carbon pollution regulations are legally mandated. In 2007, the US Supreme Court ruled that if it determined that carbon pollution poses a threat to public health or welfare, the EPA would be required to regulate emissions of that pollution under the Clean Air Act. In 2009, the EPA issued its endangerment finding, citing several comprehensive climate science reports, correctly concluding that carbon pollution poses a threat to public health and welfare and must therefore be regulated.

So while some Republicans in Congress have called the proposed carbon pollution regulations an “executive overreach,” in reality the EPA is simply implementing the law of the land.

Doomed GOP Challenges

Senate majority leader Mitch McConnell (R-KY) introduced legislation last year to block the EPA regulations. But even if that bill could make it through Congress, it would face a certain veto by President Obama.

There’s another effort to challenge the EPA regulations in court. These recently made headlines because they involve Laurence Tribe, for whom Obama was a research assistant at Harvard. Tribe has argued that the EPA regulations violate Section 111(d) of the Clean Air Act, and the DC court of appeals has just agreed to hear the arguments.

However, the chances of success for this legal challenge are extremely slim. NRDC attorney Benjamin Longstreth told me,

I would not read anything into the Court’s decision to schedule argument. The case has not even been briefed yet (that’s ongoing) so the decision to schedule argument doesn’t reflect anyone’s view of the merits of the case (the judges who are going to decide the case won’t even have the briefs yet) ... But it is important to remember that these cases are fatally premature (an issue that Tribe doesn’t address). You can only challenge a final agency decision. Here the petitioners seek to challenge a proposed rule.

Tribe’s main argument lies in the claim that Section 111(d) of the Clean Air Act says that the EPA can’t regulate an air pollutant if it’s already regulating another pollutant from the same source. The EPA already regulates mercury emissions from power plants. However, this is an inaccurate reading of both the letter and intent of the law. Moreover, as Longstreth and his colleague David Doniger have explained, the Supreme Court has effectively already ruled on this issue (emphasis added).

This is how the Supreme Court interpreted the provision in American Electric Power v. Connecticut . There the Court held that plaintiffs could not bring a federal tort action against major electric power companies for their emissions of carbon dioxide, because the Clean Air Act authorized EPA to regulate power plants’ carbon dioxide pollution under Section 111(d).

An Easy Alternative Path

While efforts to block or challenge the legality of the EPA carbon pollution regulations are all but doomed to failure, there is one way that Republicans in Congress could get rid of those regulations at any time. President Obama told Congress that if it didn’t act to address the threat of climate change, he would. But he and congressional Democrats would rather take action via a free market solution.

With support from just a few of its Republican members, Congress could pass climate legislation that would replace the EPA regulations with a carbon pricing mechanism. Efforts were previously made (but failed by a slim margin) to implement a carbon cap and trade system. More recently, a revenue-neutral carbon tax has become the favored policy, especially among conservatives.

Click here to read the rest

from Skeptical Science http://ift.tt/1zb4q9H

Why Is Snow White? [Uncertain Principles]

It didn’t make the news, because skittish media types are mostly based in New York City and thus don’t care about anything north of Westchester County, but we had a big snow storm yesterday. It started snowing Sunday night, though, and kept up through pretty much dinnertime Monday. Both the local schools and the snow-day day-care program we signed the kids up for were shut down, with good reason- I had to go to campus for my 10:30 am class, and that two-mile drive was pretty nerve-wracking.

Since the kids were home for the day, we did a bit of playing outside, even though the temperatures were in the low double digits Fahrenheit. At one point in this, the Pip asked “Daddy, why is the snow white?” I didn’t give a great answer to that at the time, but it’s one of those little-kid questions that is sneakily really good, so it’s worth a blog post (even though it’s not like he’s going to read this…).

The whiteness of newly fallen snow is, of course, one of its primary defining characteristics, so it’s tempting to just say that, you know, that’s the way snow is. But it’s actually a pretty good question, because snow is really just frozen water, and frozen water tends to be transparent:

A row of icicles, photo from Wikimedia.

There’s a little bit of reflection off the surface of the icicles in that photo (from Wikimedia), which is what allows you to see the icicles at all, but for the most part the ice is clear.

Now, you might want to say that snow is different than ice in some way, but in fact, if you look closely enough, you see that single snowflakes are also mostly clear ice:

A single snowflake, photo from Caltech’s gallery of these.

I picked a relatively flat flake for this illustration, but Caltech’s snowflake gallery has dozens of these photos, and they’re all fundamentally similar. On a microscopic level, snowflakes are transparent, just like icicles.

So why is snow white, then? Well, it’s white because you’re basically never looking at just one snowflake, unless you’re in Ken Libbrecht’s lab taking pretty photos. When we look out the window at great drifts of snow and contemplate either jumping in them or shoveling the driveway, we’re seeing millions and millions of individual snowflakes all heaped together.

For both icicles and snowflakes, we see a little bit of reflected light coming from the surface where the air stops and the ice begins (or vice versa). With an icicle, there are only two such surfaces, so we only see a small bit of reflected light off the front. Most of the light that hits the front side of the icicle passes through, so we can clearly see light coming through from the other side and know that the ice is transparent.

A snowdrift, on the other hand, contains millions of such surfaces. Each individual snowflake only reflects a tiny bit of the light that hits it, passing most of the light through, but the light that gets through hits another snowflake, then another, and another, and another. The end result of all those tiny individual reflections is that the majority of the light hitting the front side of the snowdrift ends up bouncing back. And so, drifts of newly fallen snow appear bright white, and very little light makes it through to the other side.

(Snow isn’t completely opaque, of course, as anyone who has ever built a snow fort knows. Even a fairly thick block of snow will pass a little bit of light, providing a diffuse illumination inside. Also, all those billions of snowflakes are reflecting light in slightly different directions, which is why you can’t see your reflection in a snowdrift.)

So, why is snow white? Because there’s just so much of it. A snowflake is basically clear, just like an icicle, but a billion snowflakes in a pile look white because all of their individual reflections combine to send all the light coming in back where it came from.

from ScienceBlogs http://ift.tt/1AodGJt

It didn’t make the news, because skittish media types are mostly based in New York City and thus don’t care about anything north of Westchester County, but we had a big snow storm yesterday. It started snowing Sunday night, though, and kept up through pretty much dinnertime Monday. Both the local schools and the snow-day day-care program we signed the kids up for were shut down, with good reason- I had to go to campus for my 10:30 am class, and that two-mile drive was pretty nerve-wracking.

Since the kids were home for the day, we did a bit of playing outside, even though the temperatures were in the low double digits Fahrenheit. At one point in this, the Pip asked “Daddy, why is the snow white?” I didn’t give a great answer to that at the time, but it’s one of those little-kid questions that is sneakily really good, so it’s worth a blog post (even though it’s not like he’s going to read this…).

The whiteness of newly fallen snow is, of course, one of its primary defining characteristics, so it’s tempting to just say that, you know, that’s the way snow is. But it’s actually a pretty good question, because snow is really just frozen water, and frozen water tends to be transparent:

A row of icicles, photo from Wikimedia.

There’s a little bit of reflection off the surface of the icicles in that photo (from Wikimedia), which is what allows you to see the icicles at all, but for the most part the ice is clear.

Now, you might want to say that snow is different than ice in some way, but in fact, if you look closely enough, you see that single snowflakes are also mostly clear ice:

A single snowflake, photo from Caltech’s gallery of these.

I picked a relatively flat flake for this illustration, but Caltech’s snowflake gallery has dozens of these photos, and they’re all fundamentally similar. On a microscopic level, snowflakes are transparent, just like icicles.

So why is snow white, then? Well, it’s white because you’re basically never looking at just one snowflake, unless you’re in Ken Libbrecht’s lab taking pretty photos. When we look out the window at great drifts of snow and contemplate either jumping in them or shoveling the driveway, we’re seeing millions and millions of individual snowflakes all heaped together.

For both icicles and snowflakes, we see a little bit of reflected light coming from the surface where the air stops and the ice begins (or vice versa). With an icicle, there are only two such surfaces, so we only see a small bit of reflected light off the front. Most of the light that hits the front side of the icicle passes through, so we can clearly see light coming through from the other side and know that the ice is transparent.

A snowdrift, on the other hand, contains millions of such surfaces. Each individual snowflake only reflects a tiny bit of the light that hits it, passing most of the light through, but the light that gets through hits another snowflake, then another, and another, and another. The end result of all those tiny individual reflections is that the majority of the light hitting the front side of the snowdrift ends up bouncing back. And so, drifts of newly fallen snow appear bright white, and very little light makes it through to the other side.

(Snow isn’t completely opaque, of course, as anyone who has ever built a snow fort knows. Even a fairly thick block of snow will pass a little bit of light, providing a diffuse illumination inside. Also, all those billions of snowflakes are reflecting light in slightly different directions, which is why you can’t see your reflection in a snowdrift.)

So, why is snow white? Because there’s just so much of it. A snowflake is basically clear, just like an icicle, but a billion snowflakes in a pile look white because all of their individual reflections combine to send all the light coming in back where it came from.

from ScienceBlogs http://ift.tt/1AodGJt

Particle-Wave Duality for Eight-Year-Olds [Uncertain Principles]

Over at Scientific American’s Frontiers for Young Minds blog, they have a great post on what happens when you ask scientists to explain key elements of a different research field. It’s pretty funny, and rings very true, as SteelyKid asks me tons of science questions, very few of which have anything to do with atomic, molecular, or optical physics. so I spend a lot of time faking my way through really basic explanations of other fields.

Of course, even pitching stuff from my own field at the right level for small kids is a challenge. Which reminds me, I never did explain my presentation for the young kids at the Renaissance Weekend, and I probably ought to say something about that.

When I signed up to do stuff there, I said I’d be happy to talk to kids about science, not entirely realizing what level I was getting myself in for. they put me down to do “What Every Dog should Know About Quantum Physics” for their “camp” program, which turns out to be ages 6-12. And I had half an hour, instead of the usual hour. Which presented what you might call a formidable challenge…

I decided to try for something at least somewhat active, rather than just PowerPointing at them. Since the goal was to get a little sense of the weird-and-cool part of quantum physics, I opted to try to explain particle-wave duality via the double-slit experiment.

The wave part is easy– I carry a green laser pointer in my laptop bag basically all the time, and I borrowed a couple of double-slit slides from the teaching labs, one to pass around, and one to shine the laser through. Laser pointers in general are endlessly fascinating to little kids, and seeing it go through slits and make lots of spots is way cool.

How to do the particle half, though? Well, I remembered a public talk I saw at the Perimeter Institute ages and ages ago where one of their outreach folks gave a talk on quantum, and talked about doing the double-slit with progressively smaller things. At one stage, he was imagining doing it with grains of sand, and passed a pinch of sand to people in the front row, “In case you need to remind yourself how big a grain of sand is…”

So, I latched onto that, and produced this:

Experimental set-up for the double-slit experiment with classical particles (salt crystals).

That’s a double-slit experiment done with particles that are small, but undeniably classical particles. For this test at home, I used table salt; at the actual event, I used colored sugar. I cut a couple of slits in a piece of cardboard, propped it up on a stand (actually the box for my laser pointer), and poured particles through. You can see a big pile on the top, because only a fraction of the particles made it through the slits, and two distinct piles down below. Which is exactly what you expect for classical particles that have to go through either one slit or the other.

So, I had live demos for both particle and wave behaviors, and could then go to Hitachi’s awesome single-electron interference video to show the quantum version. Which I think works to make the key point: when you get down to really small things, the rules change, and you get the weird quantum case, that’s both particle-like and wave-like at the same time.

How did it work in practice? Kind of a mixed bag.

For one thing, I had somewhat overestimated the audience– the median age of the kids was probably eight. The handful of slightly older kids were duly impressed, but the younger ones mostly just wanted to eat the colored sugar. I also had had to remove most of the dog material, which was a mistake– if I ever need to do this again, I’ll lead into it with some additional cute-dog photos.

I’m not quite sure how I would end up needing to do this again, but I’d be willing to give it another shot, so if you’d like me to talk quantum physics to second-graders, drop me a line. But really, if I go to Charleston again and find myself speaking to the campers, I’ll probably stick with the classical physics of sports equipment…

(Completely independent of this, I do have an idea for a way to introduce quantum physics to the picture-book set, which I’d be happy to talk about to anybody who might have the art skills to help make such a thing…)

from ScienceBlogs http://ift.tt/1ED34bd

Over at Scientific American’s Frontiers for Young Minds blog, they have a great post on what happens when you ask scientists to explain key elements of a different research field. It’s pretty funny, and rings very true, as SteelyKid asks me tons of science questions, very few of which have anything to do with atomic, molecular, or optical physics. so I spend a lot of time faking my way through really basic explanations of other fields.

Of course, even pitching stuff from my own field at the right level for small kids is a challenge. Which reminds me, I never did explain my presentation for the young kids at the Renaissance Weekend, and I probably ought to say something about that.

When I signed up to do stuff there, I said I’d be happy to talk to kids about science, not entirely realizing what level I was getting myself in for. they put me down to do “What Every Dog should Know About Quantum Physics” for their “camp” program, which turns out to be ages 6-12. And I had half an hour, instead of the usual hour. Which presented what you might call a formidable challenge…

I decided to try for something at least somewhat active, rather than just PowerPointing at them. Since the goal was to get a little sense of the weird-and-cool part of quantum physics, I opted to try to explain particle-wave duality via the double-slit experiment.

The wave part is easy– I carry a green laser pointer in my laptop bag basically all the time, and I borrowed a couple of double-slit slides from the teaching labs, one to pass around, and one to shine the laser through. Laser pointers in general are endlessly fascinating to little kids, and seeing it go through slits and make lots of spots is way cool.

How to do the particle half, though? Well, I remembered a public talk I saw at the Perimeter Institute ages and ages ago where one of their outreach folks gave a talk on quantum, and talked about doing the double-slit with progressively smaller things. At one stage, he was imagining doing it with grains of sand, and passed a pinch of sand to people in the front row, “In case you need to remind yourself how big a grain of sand is…”

So, I latched onto that, and produced this:

Experimental set-up for the double-slit experiment with classical particles (salt crystals).

That’s a double-slit experiment done with particles that are small, but undeniably classical particles. For this test at home, I used table salt; at the actual event, I used colored sugar. I cut a couple of slits in a piece of cardboard, propped it up on a stand (actually the box for my laser pointer), and poured particles through. You can see a big pile on the top, because only a fraction of the particles made it through the slits, and two distinct piles down below. Which is exactly what you expect for classical particles that have to go through either one slit or the other.

So, I had live demos for both particle and wave behaviors, and could then go to Hitachi’s awesome single-electron interference video to show the quantum version. Which I think works to make the key point: when you get down to really small things, the rules change, and you get the weird quantum case, that’s both particle-like and wave-like at the same time.

How did it work in practice? Kind of a mixed bag.

For one thing, I had somewhat overestimated the audience– the median age of the kids was probably eight. The handful of slightly older kids were duly impressed, but the younger ones mostly just wanted to eat the colored sugar. I also had had to remove most of the dog material, which was a mistake– if I ever need to do this again, I’ll lead into it with some additional cute-dog photos.

I’m not quite sure how I would end up needing to do this again, but I’d be willing to give it another shot, so if you’d like me to talk quantum physics to second-graders, drop me a line. But really, if I go to Charleston again and find myself speaking to the campers, I’ll probably stick with the classical physics of sports equipment…

(Completely independent of this, I do have an idea for a way to introduce quantum physics to the picture-book set, which I’d be happy to talk about to anybody who might have the art skills to help make such a thing…)

from ScienceBlogs http://ift.tt/1ED34bd