As much as people might try, things don’t always go to plan when it comes to sex – the condom breaks, someone forgot to take their pill that day, or people just get a bit lost in the moment. Not everyone wants a baby to come out of such situations, and that’s where emergency contraception comes in.What is emergency contraception?Emergency contraception refers to methods of contraception that can be used to prevent pregnancy in all sorts of situations. The first things that come to mind for many people would be unprotected sex or a condom breaking or slipping off, but it can also be used when people have missed doses of their regular hormonal contraception, a contraceptive coil or implant has fallen out, or in cases of sexual assault.There are two main types of emergency contraception. The first is the “morning-after pill”, which can actually be one of two kinds of oral medication. These are levonorgestrel, more commonly known under brand names like Plan B One-Step or Levonelle; and ulipristal acetate, known as ella or ellaOne.The second type is the intrauterine device (IUD), also called the copper coil, which is placed into the uterus. Whereas emergency contraceptive pills can be picked up at pharmacies or on prescription, IUDs need to be fitted by a healthcare professional.How does emergency contraception work?What emergency contraception doesn’t do is end a pregnancy – that’s the realm of abortion pills – nor does it protect against sexually transmitted infections.Emergency contraceptive pillsBoth kinds of emergency contraceptive pill work to delay ovulation – the release of an egg from an ovary – in order to prevent pregnancy, but they do so in different ways.Levonorgestrel is a synthetic hormone that works to stop a surge of luteinizing hormone, the chemical messenger that triggers ovulation. By blocking the surge, the release of an egg is either delayed or stopped as a result.Ulipristal acetate is a non-hormonal drug that prevents the effects of progesterone, a hormone that’s also involved in the menstrual cycle. It does this by binding to the body’s progesterone receptors, which in turn suppresses or delays ovulation.The IUDThe IUD is a non-hormonal method of emergency contraception that works by releasing copper into the uterus, which stops sperm from being able to survive there and continue its journey to fertilize an egg. On the rare occasion that sperm does survive and fertilize an egg, the presence of an IUD can stop it from implanting into the womb lining by thinning it.How effective is emergency contraception?No form of emergency contraception has a 100 percent chance of preventing pregnancy, but the IUD is pretty much the closest you can get – when inserted within five days of unprotected sex, it’s more than 99 percent effective.Despite being colloquially known as the “morning-after pill”, levonorgestrel can actually be taken up to three days after unprotected sex, and ulipristal up to five days, and still have a chance at preventing pregnancy. That being said, levonorgestrel is more effective the sooner it’s taken – it’s 95 percent effective when taken within 24 hours of unprotected sex, but that effectiveness drops down to 58 percent when taken within 49 to 72 hours. On the other hand, ulipristal doesn’t become less effective over time provided it is taken within the five days recommended and is 98 to 99 percent effective at preventing pregnancy during this window.However, it’s important to remember that for both emergency contraceptive pills, neither is likely to be effective if taken after ovulation – but ovulation can be tricky to predict, so it’s often recommended to use emergency contraception regardless of where someone is in their cycle.Similarly, there’s also been some evidence to suggest that having a BMI classified as overweight or obese could make emergency contraceptive pills – particularly levonorgestrel – less effective, but it’s still recommended that emergency contraception can be used. The IUD isn’t known to be affected by body weight.People who vomit two to three hours after taking an emergency contraceptive pill will also need to take another dose in order for it to be effective.How safe is emergency contraception?Emergency contraception is safe for most people, but there are some who it’s not suitable for. For example, ulipristal isn’t suitable for people taking steroidal asthma medications, and also may not work for people taking certain medications for epilepsy, HIV, or tuberculosis. The IUD can’t be used for people with certain untreated infections, cervical or uterus abnormalities, or unexplained vaginal bleeding. They also carry some uncommon risks like the uterus pushing the IUD out or, rarely, the device damaging the uterus.Like any medicine, emergency contraception can also have some side effects. For the IUD, there’s a chance of period-like pains in the days following its insertion, and if someone decides to keep it as a longer-term form of contraception, bleeding between periods or heavier, longer periods.Emergency contraceptive pills can come with side effects like headache, nausea and vomiting, dizziness, tiredness, tender breasts, or abdominal pain.All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.The content of this article is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of qualified health providers with questions you may have regarding medical conditions.

It came from the same sunspot that caused the spectacular aurorae earlier in 2024. Read more here.

The quest to find “missing matter” in the universe has been unsuccessful so many times that some exotic suggestions get taken more seriously than they once might. As Sherlock Holmes famously said, “When you have eliminated the impossible whatever remains, however, improbable, must be the truth.” In this case, there are many improbable ideas being tested to see if they’re impossible.  One that has attracted enough attention that IFLScience was asked to discuss it is Dyson Spheres. There are good reasons to conclude these hypothetical spheres are not the matter you are looking for, but also to explore how we know that.First, What’s A Dyson Sphere?Only a tiny fraction of the Sun’s energy falls on its planets, with the rest escaping into space. In 1937, science fiction writer Olaf Stapledon wrote a book, The Star Maker, that explored ideas of vastly more advanced civilizations’ quest for energy. The book inspired the physicist Freeman Dyson to propose that such civilizations might build giant thin surfaces in space to capture more of their stars’ energy, eventually partially or entirely encircling the star. Dyson noted that such structures would block the visible light from the star to observers elsewhere, but would radiate in infrared. Consequently, he argued, a way to find advanced extraterrestrial civilizations might be to look for infrared-dominated spectra.The idea captured a lot of people’s imaginations and achieved a surge in popularity when the mystery of KIC 8462852 (also known as Boyajian’s star) emerged in 2015. KIC 8462852 undergoes significant dips in brightness on irregular intervals, far too large to be the result of planets blocking its light. There was so much speculation that the observed behavior might be caused by a partially-constructed Dyson Sphere, that another nickname, the “Alien Megastructure Star”, became common.What Is The Missing Mass?There are actually two sorts of mass our surveys of the local universe have failed to find. The more famous of these is dark matter, the mass needed to explain the movements of galaxies under the laws of gravity. The other sort of missing mass is more regular material, probably mostly composed of hydrogen and helium, unlike dark matter, which is most likely to be exotic particles. When astronomers talk about “missing mass”, they mean the second sort. We know that this category is made of regular elements because evidence from shortly after the birth of the universe allows us to calculate how much ordinary matter there should be in the universe today. When we look around us we can only see about two-thirds of that amount.There is a lot less mass missing in this category than dark matter, but still an awful lot of it. Among the explanations are enormous filaments of gas stretching between galaxiesSo Could Dyson Spheres Account For Either Sort Of Missing Mass?Sadly, almost certainly not.Once people got over how cool Dyson Spheres would be, and having fun with the potential science fiction ideas of living on the inside of something so mind-blowingly huge, physicists contemplated the practicalities. And it turns out that complete Dyson Spheres just don’t make sense.The material for a Dyson Sphere would need to come from somewhere. It’s very unlikely that even the most advanced civilization would be able to scoop matter from their star and turn it into something solid. If they could, they probably wouldn’t be relying on stellar energy anyway. Therefore, the material of the Sphere would need to be made of planets, moons, and asteroids.Some star systems have more mass in orbit than ours, others probably less. But there’s no reason to think we’re unusually light in that department.That means that there wouldn’t be all that much mass in the sphere itself, even if you used every scrap of solid material in the planetary system. If the question was intended to mean “Could the material in Dyson Spheres be so enormous it accounts for a large portion of the missing matter?” then you’d have to explain where that matter came from in the first place. Scouring the space between the stars and finding rogue planets or other sources of material so they could be turned into backing for solar panels is unlikely to be practical.The other way to interpret the question is: “Could there be billions of stars surrounded by Dyson Spheres that catch all their light so we can’t see them, thus making the galaxy much more densely packed with stars than we think?” That’s generally what people mean.The popular, but almost certainly incorrect, vision of the Dyson Sphere, is one that gets steadily built up until the star is surrounded by a complete sphere.Image Credit: Rebekah Smith CC BY-SA 2.0However, given the amount of solid material in the Solar System, any completely encircling Sphere would have to be very thin. So thin, in fact, that it would be gravitationally unstable. The only way to avoid disaster would be to use vast amounts of energy, making the whole idea a net loss.If Dyson Spheres exist at all, they’re very incomplete, either thin “Dyson Rings”, or networks of patches collecting a few percent or less of the star’s light. These are sometimes referred to as Dyson Swarms. Were a star orbited by a Dyson Swarm, we would see it, dimmed by the occasional blip as the portion got between us and it – the hypothetical situation that made KIC 8462852 famous. Dozens of stars have been identified where this could be happening, although other explanations are more likely.In a case like this, the star would not go missing for any extended period. Consequently, our estimates of the number of stars in the galaxy would not be wrong by much, if at all. Any small undercount could only be responsible for a tiny proportion of the missing matter.Even if a complete Dyson Sphere was built, an essential feature of the concept is that it would radiate in the infrared. Dyson wanted us to be on the lookout for that sort of infrared signal. The JWST and our few other infrared telescopes cannot be looking everywhere so they may have missed a few such radiators. However, if these were common enough to solve the mystery of the missing mass, we should have seen them by now.

The PBS News Hour crew is clearly heartsick that the Democrats are in a crisis over Joe Biden's mental decline, and they know their liberal audience wants to change the subject back to Horrible Trump. Sounding like a taxpayer-funded MSNBC host, PBS anchor Amna Nawaz described the former president as an authoritarian full of lies in the Friday pundit roundtable with liberal David Brooks and more liberal Kimberly Atkins Stohr. Can anyone imagine how Nawaz might explode in rage if anyone actually was allowed to voice a Republican view on PBS? Mock Democrats for not being democratic? For being incompetent at governing? After a few minutes of talking about the Biden crisis, Nawaz uncorked it: NAWAZ: Biden backers have told me, look, they're worried that the focus on this conversation takes the focus off of Trump, who is an antidemocratic candidate with authoritarian tendencies, who is now newly empowered by that Supreme Court immunity ruling. The head of The Heritage Foundation, we should point out, that's running this Project 2025 policy planning for a potential second Trump term, said this, this week. He said the country is in what he called the second American revolution-, and it could be — quote — "bloodless if the Left allows it to be." There's kind of this alarming language around a potential Trump presidency. Are we losing sight of the stakes here? The Democrats seized on the comments of Kevin Roberts, who was describing the tendency of the Left to riot. In reaction, the Heritage Foundation tweeted a video full of Democrat talk of violence and support of the rioting in 2020. Like an MSNBC host, Nawaz can't imagine she is using "alarming language" about the "antidemocratic candidate with authoritarian tendencies," or that her friends relentlessly comparing Trump to Hitler is alarming or inflammatory. But naturally, David Brooks agreed. He only made the ladies on set uncomfortable by citing bad poll numbers.  BROOKS: Yes, I think so. I mean, I — before he went to prison, I went over to see Steve Bannon and interviewed him. And I was scared out of my mind. Like, I just asked him, what's going to happen if you guys win? And he said: It'll be nothing like 2017. In 2017, we didn't have staff. We had nothing. But now we have got people who have been vetted. We have got people who are trained and we're just going to go after the deep state. It looked like a dismantling of the civil service, basically. And that's just the beginning. So I do think people are losing some focus on that. And I have been a broken record on this for, whatever, seven years. But it is also true that every American pretty much has seen an elderly relative in decline. And they sort of know what that looks like. And if I could just do one bit just random polling, as I mentioned, 72 percent of Americans don't think he should run again.  Brooks noted that Trump is leading by six points in several polls from "mainstream" outlets. Then Nawaz returned to another Democrat Party line of the week, of "asymmetry," that somehow Democrats are having a debate about replacing Biden, while Republicans don't budge on Trump. But Republicans had an actual primary race. Democrats suppressed primaries, and allowed no primary debates. NAWAZ: I want to get back to this issue of how we're talking about President Trump as well here, which is to say there seems to be sort of an asymmetry of expectations as well in terms of Trump's performance in the debate, which was filled with misleading statements and lies. He's only three years younger than President Biden, often veers off-script when he's not on prompter. Is — do you see that asymmetry? Is that affecting the conversation right now, Kim? KIMBERLY ATKINS STOHR: I 100 percent see that asymmetry. Look, we can talk about mental cognitive tests that people might want the president to take, but we already know that Donald Trump has failed the moral test. He's failed the democracy test. He's failed the insurrection test. And if we balance those things, it seems really clear. And I think one thing that this conversation makes us lose sight of is the fact the work of the Biden administration and other Democrats being already dismantled ever since the Supreme Court overturned Chevron just earlier this week. We already have two federal judges, Republican-appointed federal judges, one that knocked down a rule that kept people from being bound by non-compete clauses that would prevent them from practicing their livelihoods, another rule that prevented federal coverage of transgender health care. This is happening right now. This is happening this week. The dominoes are already falling, and we haven't even gotten to Project 2025.

The surgeon general wants to promote gun control through public health. He should try to get his facts right first.

Conservatives in the U.K., especially Rishi Sunak, contributed to their own failure. But we should hope that doesn’t last too long.

The Constitution does not empower executive officers to create inferior-officer positions absent an enabling statute.

A Vivian Maier show, New York’s first, and looking at People at 50.

Factional chaos with no clear majority is the likeliest outcome.

College athletics is on the brink of momentous change. But schools shouldn’t yield to pressure to eliminate academic life for athletes entirely.