Why do we have leap years? This question came from a reader submission (thanks Shi So!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐ The short answer Leap years exist because a full orbit around the Sun takes 365.242189 days, so we add extra days to keep our calendar aligned with the seasons. The Gregorian calendar uses specific leap year rules to stay closely synced with the solar year, skipping three leap years every 400...
10 days agoย โขย 5 min read
What causes dark circles under your eyes? This question came from a reader submission (thanks Aastha!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐ The short answer Dark circles under the eyes can result from true hyperpigmentationโcaused by excess melanin, iron deposits, skin thickening, or visible blood vesselsโor from shadowing effects due to changes in under-eye volume like hollowness or puffiness. ๐ The long answer Perhaps...
17 days agoย โขย 7 min read
What made old Nokia phones nearly indestructible? This question came from a reader submission (thanks Jana!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐ The short answer The Nokia 3310 was nearly indestructible thanks to its rugged double-shell plastic design, compact build, recessed screen, non-glued components, single Printed Circuit Board, and a company-wide emphasis on durability and reliability. ๐ The long answer As...
24 days agoย โขย 5 min read
Why are teenagers so impulsive? This question came from a reader submission (thanks Linux!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐ The short answer Teenagers are more impulsive because their brains are still developing faster access to the parts responsible for self-control, while emotion and reward systems are already firing on all cylinders. Hormone spikes, limited life experience, and peer pressure also contribute to...
about 1 month agoย โขย 6 min read
Can you cook pasta without boiling water? This question came from a reader submission (thanks Marc!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐ The short answer Yes, the key chemical reactions that cook pasta happen at around 180ยฐF (82ยฐC), below the boiling point of water (212ยฐF (100ยฐC)). But cooking pasta at this lower temperature will require you to cook for a longer time. ๐ The long answer On the package of your favorite...
about 1 month agoย โขย 6 min read
Why does oversleeping make you tired? This question came from a reader submission (thanks Rodrigo!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐ The short answer Oversleeping can make you feel more tired because it throws off your internal clock. You might wake up during a deep sleep stage, miss your bodyโs natural cortisol boost that helps you feel alert, and wake up dehydrated โ all of which can cause you to feel tired. ๐ The...
about 2 months agoย โขย 5 min read
Why do flies rub their legs together? ๐ The short answer Flies rub their legs together to clean off dust, dirt, moisture, and pollen that can interfere with their senses. Staying clean helps them fly, avoid infections, an taste with their feet. ๐ The long answer You've probably spotted a fly rubbing its little legs together and wondered what that's all about. The options run through your head (memes linked for illustrative effect): (A) Plotting world domination (B) Gearing up for a delicious...
about 2 months agoย โขย 4 min read
Longtime readers of Today You Should Know may recognize this question โ it's a repeat! I just returned from a fantastic trip seeing lovely people and climbing beautiful mountains. Not one word was written as I focused on being present. Hope you enjoy (re)learning about why the U.S. eats quarter pounders and not ... 113 grammers ๐. Back next week with a new curious question. ๐ Caitlin Why doesn't the U.S. use the metric system? ๐ The short answer Pirates are a big reason why the United States...
about 2 months agoย โขย 5 min read
What does shaving cream do? This question came from a reader submission (thanks Saurav ๐!). Has a curious question stumped you lately? Feel free to submit your own question here: Submit your question ๐ The short answer Shaving cream is a specially designed soap that forms a dense, long-lasting foam. It lifts hairs for a smoother, closer shave, hydrates and protects your skin, and cleans away oils and debris as you go. ๐ The long answer Humans have been shaving for thousands of years, but the...
2 months agoย โขย 5 min read