Why Can I Sometimes See the Moon During the Day?

Chloe Effron
Chloe Effron

WHY? is our attempt to answer all the questions every little kid asksHave a question? Send it to why@mentalfloss.com.

The Sun comes out in the morning and sets at night, and then the Moon rises. Right? Then how come we can see the Moon during the day sometimes? 

The Moon and the Sun don’t actually take turns in the sky. The Earth orbits around the Sun, and the Moon orbits around the Earth. All three are spinning in space all the time. When the part of the Earth you're standing on faces the Sun, the sky is filled with sunlight. That's daytime. When your part of the planet is turned away from the Sun, that's night time. The Moon moves through the sky night and day. Much of the time, the sunlight is so bright, we can't see the Moon during the day.

The Sun is a very hot ball of gas. Like a fire or a light bulb, the Sun gives off both heat and light. But the Moon is made of rock, not gas, and it is not hot or bright at all. What we call moonlight is actually sunlight bouncing off the Moon, the same way that sunlight bounces off the reflectors on your bike. They look like they’re lighting up, but they’re really just passing the sunlight along.

How bright the Moon is depends on where it is in the sky. If the Moon is between the Earth and the Sun, it doesn’t bounce any sunlight to us at all, and it is very hard to see, even at night. This is called a new moon. When the Moon is behind the Earth, it shines very brightly. We call this a full moon. You can see in this video how the Moon gets different amounts of sunlight as it orbits around the Earth. That changes how it looks to us. Sometimes, when the Moon is very bright, we can see it even during the daytime.

Let's try an experiment! Tonight, get a flashlight and go into your room. (Bring your mom or dad with you if that seems a little scary.) Turn off the lights, and turn on the flashlight. You'll notice that it’s very easy to see the bright light of the flashlight. Keep the flashlight on, then turn the room lights back on. Now the light from the flashlight is a lot harder to see. It's the same with the Moon. At night, it’s easy to see the Moon, because it’s the brightest thing in the sky. But during the day, the Moon has to be very bright for us to notice it. That means that the best time to see a daytime moon is in the morning just before and just after the full moon. 

To learn more about the Moon and light, visit the Science Trek Moon Facts web page.

No Venom, No Problem: This Spider Uses a Slingshot to Catch Prey

Courtesy of Sarah Han
Courtesy of Sarah Han

There are thousands of ways nature can kill, and spider species often come up with the most creative methods of execution. Hyptiotes cavatus, otherwise known as the triangle weaver spider, is one such example. Lacking venom, the spider manages to weaponize its silk, using it to hurl itself forward like a terrifying slingshot to trap its prey.

This unusual method was studied up close for a recent paper published in the Proceedings of the National Academy of Sciences by researchers at the University of Akron in Ohio. They say it's the only known instance of an animal using an external device—its web—for power amplification.

Hyptiotes cavatus's technique is simple. After constructing a web, the spider takes one of the main strands and breaks it in half, pulling it taut by moving backwards. Then, it anchors itself to a spot with more webbing in the rear. When the spider releases that webbing, it surges forward, propelled by the sudden release of stored energy. In the slingshot analogy, the webbing is the strap and the spider is the projectile.

This jerking motion causes the web to oscillate, tangling the spider's prey further in silk. The spider can repeat this until the web has completely immobilized its prey, a low-risk entrapment that doesn’t require the spider to get too close and risk injury from larger victims.

The triangle weaver spider doesn’t have venom, and it needs to be proactive in attacking and stifling prey. Once a potential meal lands in its web, it’s able to clear distances much more quickly using this slingshot technique than if it crawled over. In the lab, scientists clocked the spider’s acceleration at 2535 feet per second squared.

Spiders are notoriously nimble and devious. Cebrennus rechenbergi, or the flic-flac spider, can do cartwheels to spin out of danger; Myrmarachne resemble ants and even wiggle their front legs like ant antennae. It helps them avoid predators, but if they see a meal, they’ll drop the act and pounce. With H. cavatus, it now appears they’re learning to use tools, too.

[h/t Live Science]

Bad News: The Best Time of the Day to Drink Coffee Isn’t as Soon as You Wake Up


If you depend on coffee to help get you through the day, you can rest assured that you’re not the world's only caffeine fiend. Far from it. According to a 2018 survey, 64 percent of Americans said they had consumed coffee the previous day—the highest percentage seen since 2012.

While we’re collectively grinding more beans, brewing more pots, and patronizing our local coffee shops with increased frequency, we might not be maximizing the health and energy-boosting benefits of our daily cup of joe. According to Inc., an analysis of 127 scientific studies highlighted the many benefits of drinking coffee, from a longer average life span to a reduced risk for cancer, heart disease, type 2 diabetes, and Parkinson’s disease.

Sounds great, right? The only problem is that the benefits of coffee might be diminished depending on the time of day that you drink it. Essentially, science tells us that it’s best to drink coffee when your body’s cortisol levels are low. That’s because both caffeine and cortisol cause a stress response in your body, and too much stress is bad for your health for obvious reasons. In addition, it might end up making you more tired in the long run.

Cortisol, a stress hormone, is released in accordance with your circadian rhythms. This varies from person to person, but in general, someone who wakes up at 6:30 a.m. would see their cortisol levels peak in different windows, including 8 to 9 a.m., noon to 1 p.m., and 5:30 to 6:30 p.m. Someone who rises at 10 a.m. would experience cortisol spikes roughly three hours later, and ultra-early risers can expect to push this schedule three hours forward.

However, these cortisol levels start to rise as soon as you start moving in the morning, so it isn’t an ideal time to drink coffee. Neither is the afternoon, because doing so could make it more difficult to fall asleep at night. This means that people who wake up at 6:30 a.m. should drink coffee after that first cortisol window closes—roughly between 9:30 a.m. and 11:30 a.m.—if they want to benefit for a little caffeine jolt.

To put it simply: "I would say that mid-morning or early afternoon is probably the best time," certified dietitian-nutritionist Lisa Lisiewski told CNBC. "That's when your cortisol levels are at their lowest and you actually benefit from the stimulant itself."

[h/t Inc.]