A sprawling heat dome is bringing temperatures of up to 110°F, or possibly higher, to a broad swath of the U.S. on Wednesday, with more than 100 million people under heat warnings and advisories.
Driving the news: The extreme heat will be most intense in the southern Plains and lower Mississippi Valley, but the big cities of the Northeast will swelter as well.
The heat wave in Europe should best be viewed as another deadly and startling warning regarding how far we've pushed the planet's climate into less hospitable territory, and how unprepared we are for what's coming.
Catch up fast: In the past week, temperature records dating back centuries have been obliterated, particularly on Tuesday in the U.K. The heat is shifting east, into a swath of Europe extending from Germany to Sweden.
The future of NASA's aging Voyager spacecraft, which over the last 45 years have collected data no human-made probes have ever gathered, is starting to come into sharper focus.
Why it matters: Voyager 1 and Voyager 2 are the only functional human-made spacecraft currently in interstellar space.
In the midst of an unprecedented heat wave, the U.K. on Tuesday broke its national record for the highest temperature ever registered, with a provisional reading of 104.36°F (40.2°C) at London's Heathrow Airport, according to the country's weather service.
Why it matters: This is the first time the U.K. has breached this temperature that is more common in tropical and desert climates, and studies point to climate change as a key factor behind the scorchingly hot temperatures.
While the heat in Europe is garnering the most headlines, a potent heat wave is hitting the U.S. as well. The heat stretches from the Canadian border to the U.S. border with Mexico, with 100 million under heat warnings and advisories.
Driving the news: Heat warnings on Tuesday cover the entire state of Oklahoma and the vast majority of Texas, where the electrical grid will once again be tested.
Why it matters: The fact that we've arrived at this point — with deadly extreme heat virtually shutting down major industrialized nations, but without changing course to curb greenhouse gas emissions — is depressing and baffling to the scientists who have been warning about this moment for years.
The U.K. has likely endured its "warmest night," and its hottest day ever is forecast to follow on Tuesday as Europe's historic heat wave spreads north.
What's happening: Temperatures were above 25°C (77°F) in some parts of the U.K. overnight, per provisional Met Office data, as its first-ever Red warning for heat covers much of England. Temperatures could exceed 40°C (104°F) for the first time Tuesday. Southern Germany and eastern France were forecast to see similar temperatures.
Some 40 million Americans are under heat alerts due to "dangerous and intense," potentially record-breaking heat across the Plains and Mississippi Valley that's expected to expand into the Southeast this week.
The big picture: The National Weather Service issued a red flag warning for Texas, and there are heightened fire dangers in several states. Firefighters are already battling 89 large fires across 12 states. An excessive heat warning was in effect for all of Oklahoma for Tuesday, with highs of 110-112°F expected — 16°F above the state's average.
