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What is US Daylight Saving Time and When Do Clocks Change?

Technician Oleg Ryabtsev performs maintenance work on a clock in Minsk, Belarus, Saturday, March 29, 2008. (AP)
Technician Oleg Ryabtsev performs maintenance work on a clock in Minsk, Belarus, Saturday, March 29, 2008. (AP)
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What is US Daylight Saving Time and When Do Clocks Change?

Technician Oleg Ryabtsev performs maintenance work on a clock in Minsk, Belarus, Saturday, March 29, 2008. (AP)
Technician Oleg Ryabtsev performs maintenance work on a clock in Minsk, Belarus, Saturday, March 29, 2008. (AP)

Daylight saving time, a practice affecting almost 400 million people across North America, is once again in the spotlight as debates over its necessity continue. This twice-a-year ritual of adjusting clocks forward in spring and back in autumn has been ingrained in American, Canadian and Cuban life for more than a century. However, recent legislative proposals and shifting public sentiment are prompting a reevaluation of its relevance in today's society, Reuters said.
WHEN DO THE CLOCKS CHANGE?
Daylight saving time in the US and some other countries ends on Nov. 3 at 2 a.m. local time, meaning people will gain an extra hour of sleep. Mornings will be brighter but it will get dark earlier in the evening. The saying "spring forward, fall back" serves as a helpful reminder for adjusting clocks.
In the UK and other European countries, daylight saving time, also known as summer time, ends on Oct. 27.
Daylight saving time always starts on the second Sunday in March and ends on the first Sunday in November in the United States. This contrasts with the UK and European Union, where summer time begins on the last Sunday in March and ends on the last Sunday in October.
WHEN IS THE SHORTEST DAY OF THE YEAR IN 2024?
The shortest day of 2024 will be on Dec. 21, which marks the winter solstice. Daylight hours vary significantly across latitudes in the Northern Hemisphere. Areas near the North Pole will be plunged into complete darkness while southern regions will still get over 10 hours of sunshine.
Next year, daylight saving time will start on March 9 and end on Nov. 2.
WHY WAS DAYLIGHT SAVING CREATED IN THE US AND HOW DID IT START?
The modern idea of changing the clocks with the seasons can be traced back to at least the late 19th century, when New Zealand entomologist George Hudson proposed it to conserve energy and extend summer daylight hours, something which would have benefited his own hobby of collecting insects after work. The idea was slow to gain traction until World War One, when European states sought any strategies to conserve fuel. Germany was the first country to adopt daylight saving time in 1916. The United States followed in 1918.
The practice went through many variations before the United States standardized it in 1966 in the Uniform Time Act, which allows states to opt out of it but not to stay on daylight saving time permanently.
WHY IS DAYLIGHT SAVING TIME CONTROVERSIAL?
A common myth is that the US adopted daylight saving time to benefit farmers, but in reality many farmers are opposed to the practice for being disruptive to their schedules. The original motivation to conserve fuel is also under debate, as studies have found little, if any, energy savings from the shift, according to the US Congressional Research Service. Opponents point to other studies that have found adverse health effects linked to daylight saving time, such as a spike in fatal traffic accidents, heart attacks, strokes and sleep deprivation in the days after clocks are moved forward an hour every March.
A March 2023 YouGov poll found that 62% of Americans want to end the practice of changing clocks, though only 50% preferred to keep permanent daylight saving time.
DO ALL US STATES OBSERVE DAYLIGHT SAVING TIME?
No. Hawaii and Arizona, with the exception of the Navajo Nation, do not observe daylight saving time. The US territories of American Samoa, Guam, the Northern Mariana Islands, Puerto Rico and the US Virgin Islands also observe permanent standard time. While daylight saving time is widespread across the United States, 19 states have passed legislation to permanently use daylight saving time if Congress were to allow it, according to the National Conference of State Legislatures.
IS THE US ENDING DAYLIGHT SAVING TIME?
The United States is not ending daylight saving time any time soon, though there is proposed federal legislation called the Sunshine Protection Act that would make daylight saving time permanent. The legislation, introduced by a bipartisan group of senators, was passed by the Senate in 2022 but stalled in the US House of Representatives because lawmakers could not agree on whether to keep standard time or permanent daylight saving time.
The group of senators reintroduced the bill last year and it has been referred to the Committee on Commerce, Science and Transportation to review. The bill would need to pass the Senate and House before President Joe Biden could sign it into law.

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NASA's Europa Clipper Spacecraft will Scour Jupiter Moon for the Ingredients for Life

This illustration provided by NASA depicts the Europa Clipper spacecraft over the moon, Europa, with Jupiter at background left. (NASA/JPL- Caltech via AP)
This illustration provided by NASA depicts the Europa Clipper spacecraft over the moon, Europa, with Jupiter at background left. (NASA/JPL- Caltech via AP)
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NASA's Europa Clipper Spacecraft will Scour Jupiter Moon for the Ingredients for Life

This illustration provided by NASA depicts the Europa Clipper spacecraft over the moon, Europa, with Jupiter at background left. (NASA/JPL- Caltech via AP)
This illustration provided by NASA depicts the Europa Clipper spacecraft over the moon, Europa, with Jupiter at background left. (NASA/JPL- Caltech via AP)

A NASA spacecraft is ready to set sail for Jupiter and its moon Europa, one of the best bets for finding life beyond Earth.

Europa Clipper will peer beneath the moon’s icy crust where an ocean is thought to be sloshing fairly close to the surface. It won’t search for life, but rather determine whether conditions there could support it. Another mission would be needed to flush out any microorganisms lurking there.

“It’s a chance for us to explore not a world that might have been habitable billions of years ago, but a world that might be habitable today — right now,” said program scientist Curt Niebur, The AP reported.

Its massive solar panels make Clipper the biggest craft built by NASA to investigate another planet. It will take 5 1/2 years to reach Jupiter and will sneak within 16 miles (25 kilometers) of Europa's surface — considerably closer than any other spacecraft.

Liftoff is targeted for this month aboard SpaceX’s Falcon Heavy rocket from NASA’s Kennedy Space Center. Mission cost: $5.2 billion.

Europa, the superstar among Jupiter’s many moons One of Jupiter’s 95 known moons, Europa is almost the size of our own moon. It's encased in an ice sheet estimated to be 10 miles to 15 miles or more (15 kilometers to 24 kilometers) thick. Scientists believe this frozen crust hides an ocean that could be 80 miles (120 kilometers) or more deep. The Hubble Space Telescope has spotted what appear to be geysers erupting from the surface. Discovered by Galileo in 1610, Europa is one of the four so-called Galilean moons of Jupiter, along with Ganymede, Io and Callisto.

Seeking conditions that support life What type of life might Europa harbor? Besides water, organic compounds are needed for life as we know it, plus an energy source. In Europa’s case that could be thermal vents on the ocean floor. Deputy project scientist Bonnie Buratti imagines any life would be primitive like the bacterial life that originated in Earth’s deep ocean vents. “We will not know from this mission because we can’t see that deep,” she said. Unlike missions to Mars where habitability is one of many questions, Clipper’s sole job is to establish whether the moon could support life in its ocean or possibly in any pockets of water in the ice.

Supersized spacecraft When its solar wings and antennas are unfurled, Clipper is about the size of a basketball court — more than 100 feet (30 meters) end to end — and weighs nearly 13,000 pounds (6,000 kilograms). The supersized solar panels are needed because of Jupiter’s distance from the sun. The main body — about the size of a camper — is packed with nine science instruments, including radar that will penetrate the ice, cameras that will map virtually the entire moon and tools to tease out the contents of Europa’s surface and tenuous atmosphere. The name hearkens to the swift sailing ships of centuries past.

Circling Jupiter to fly by Europa The roundabout trip to Jupiter will span 1.8 billion miles (3 billion kilometers). For extra oomph, the spacecraft will swing past Mars early next year and then Earth in late 2026. It arrives at Jupiter in 2030 and begins science work the next year. While orbiting Jupiter, it will cross paths with Europa 49 times. The mission ends in 2034 with a planned crash into Ganymede — Jupiter’s biggest moon and the solar system's too.

Europa flybys pose huge radiation risk There’s more radiation around Jupiter than anywhere else in our solar system, besides the sun. Europa passes through Jupiter’s bands of radiation as it orbits the gas giant, making it especially menacing for spacecraft. That’s why Clipper’s electronics are inside a vault with dense aluminum and zinc walls. All this radiation would nix any life on Europa’s surface. But it could break down water molecules and, perhaps, release oxygen all the way down into the ocean that could possibly fuel sea life.

Earlier this year, NASA was in a panic that the spacecraft's many transistors might not withstand the intense radiation. But after months of analysis, engineers concluded the mission could proceed as planned.

Other visitors to Jupiter and Europa NASA’s twin Pioneer spacecraft and then two Voyagers swept past Jupiter in the 1970s. The Voyagers provided the first detailed photos of Europa but from quite a distance. NASA’s Galileo spacecraft had repeated flybys of the moon during the 1990s, passing as close as 124 miles (200 kilometers). Still in action around Jupiter, NASA’s Juno spacecraft has added to Europa’s photo album. Arriving at Jupiter a year after Clipper will be the European Space Agency’s Juice spacecraft, launched last year.

Ganymede and other possible ocean worlds Like Europa, Jupiter’s jumbo moon Ganymede is thought to host an underground ocean. But its frozen shell is much thicker — possibly 100 miles (160 kilometers) thick — making it tougher to probe the environment below. Callisto’s ice sheet may be even thicker, possibly hiding an ocean. Saturn’s moon Enceladus has geysers shooting up, but it’s much farther than Jupiter. Ditto for Saturn’s moon Titan, also suspected of having a subterranean sea. While no ocean worlds have been confirmed beyond our solar system, scientists believe they’re out there — and may even be relatively common.

Messages in a cosmic bottle Like many robotic explorers before it, Clipper bears messages from Earth. Attached to the electronics vault is a triangular metal plate. On one side is a design labeled “water words” with representations of the word for water in 104 languages. On the opposite side: a poem about the moon by US poet laureate Ada Limon and a silicon chip containing the names of 2.6 million people who signed up to vicariously ride along.