Why Do the Sun and the Moon Appear to be the Same Size?

istock.com/1001slide
istock.com/1001slide

It’s just kind of a strange coincidence. The diameter of the Sun is about 400 times larger than the Moon's, but it is also roughly 400 times farther away from Earth. These two qualities almost cancel each other out, and the Sun usually winds up looking either the same size or just a wee bit bigger than the moon to us.

How do we know how far away and how big the Sun and Moon are in the first place?

Since we can’t just wrap a giant measuring tape around a celestial body, we have to get a little creative.

Look up at the sky and imagine it as a big dome, which goes all away around the Earth, with the Sun, Moon and stars projected onto its surface. This is a neat little hypothetical that astronomers call the celestial sphere. If we think of the sphere as being 360 degrees, like a circle, we can talk about the things we see on the dome in terms of angular size (that is, the “visual diameter” of the object measured as an angle) and angular distance (the distance separating two objects measured as an angle).

We’ve been able to get a better handle on the actual distance thanks to spaceflight and laser and radar technology. For the Moon, Apollo astronauts left retro-reflectors on its surface, which we bounced lasers off of from 1969 to 2009. By timing how long it took for the laser beam to make the trip there and back, astronomers could work out the Moon’s physical distance.

For the Sun, we tried the same sort of thing and bounced radio waves off it, but the star’s outer atmosphere scattered the waves too much for accurate measurements. Astonomers switched to a more reliable method that uses German astronomer Johannes Kepler’s Third Law of Planetary Motion, observations of the other planets’ movements, and radar measurements of their distances to work out an indirect, but accurate, measurement for the distance of the Sun.

Once we have the angular size of something in the sky and its actual distance, we can use them to calculate the object’s physical diameter.

But don't get used to them looking this way

The Sun and Moon didn’t always look so close in size from Earth, though, and they won’t continue to do so forever. The Moon is moving away from Earth at a rate of about 4 centimeters per year. In a few billion years, our descendants won’t be looking up at the same sky we are, and the size difference between the Sun and Moon will be much more noticeable.

Kodak’s New Cameras Don't Just Take Photos—They Also Print Them

Your Instagram account wishes it had this clout.
Your Instagram account wishes it had this clout.
Kodak

Snapping a photo and immediately sharing it on social media is definitely convenient, but there’s still something so satisfying about having the printed photo—like you’re actually holding the memory in your hands. Kodak’s new STEP cameras now offer the best of both worlds.

As its name implies, the Kodak STEP Instant Print Digital Camera, available for $70 on Amazon, lets you take a picture and print it out on that very same device. Not only do you get to skip the irksome process of uploading photos to your computer and printing them on your bulky, non-portable printer (or worse yet, having to wait for your local pharmacy to print them for you), but you never need to bother with ink cartridges or toner, either. The Kodak STEP comes with special 2-inch-by-3-inch printing paper inlaid with color crystals that bring your image to life. There’s also an adhesive layer on the back, so you can easily stick your photos to laptop covers, scrapbooks, or whatever else could use a little adornment.

There's a 10-second self-timer, so you don't have to ask strangers to take your group photos.Kodak

For those of you who want to give your photos some added flair, you might like the Kodak STEP Touch, available for $130 from Amazon. It’s similar to the regular Kodak STEP, but the LCD touch screen allows you to edit your photos before you print them; you can also shoot short videos and even share your content straight to social media.

If you want to print photos from your smartphone gallery, there's the Kodak STEP Instant Mobile Photo Printer. This portable $80 printer connects to any iOS or Android device with Bluetooth capabilities and can print whatever photos you send to it.

The Kodak STEP Instant Mobile Photo Printer connects to an app that allows you to add filters and other effects to your photos. Kodak

All three Kodak STEP devices come with some of that magical printer paper, but you can order additional refills, too—a 20-sheet set costs $8 on Amazon.

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What Is the Citizenship of a Baby Born on an International Flight?

Nadezhda1906/iStock via Getty Images
Nadezhda1906/iStock via Getty Images

It's pretty standard medical advice: a pregnant woman shouldn’t travel via airplane 36 weeks or later into her pregnancy. Despite that precaution, an occasional bundle of joy may still add an unexpected passenger to the flight manifest. As if giving birth at 40,000 feet wasn't already a stressful experience for a new mom, things can get even more hectic upon landing: Depending on the details surrounding the birth, her newborn’s citizenship could be up for debate.

There is no universal rule for how a country determines the citizenship of a newborn. Some countries just follow the jus sanguinis (right of blood) law, which means a baby’s nationality is determined by that of one or both parents. Others observe that rule and jus soli (right of the soil), where a country grants citizenship to a baby that’s simply born on its soil, regardless of the parents’ origin. These countries are mostly in the Americas and include the United States and Canada. And with the expansion of air travel, these laws had to extend to the heavens as well.

If a baby is born over United States airspace, the jus soli rule means the child would be granted U.S. citizenship, according to the Department of State Foreign Affairs Manual. Depending on the circumstances, the child may also be a candidate for dual citizenship if its parents are from a country that grants citizenship based on blood—though that would depend on the countries involved.

This same simplicity doesn’t extend to a jus sanguinis country, though. This means that an American mother can’t attain French citizenship for her baby just because she gave birth over French airspace. The baby would simply revert to the parent's U.S. citizenship, since the United States also generally follows jus sanguinis when a baby is born to U.S. citizens in a foreign country. Since jus sanguinis is the far more common rule around the globe, most babies born on a flight over international waters or foreign airspace will likely wind up taking the citizenship of its parents.

If there’s a case where the child could potentially be stateless—such as when a mother herself has no official citizenship and the baby is born in international airspace—the baby would likely take the citizenship of whatever country the plane itself is registered in, according to the United Nations’s Convention on the Reduction of Statelessness agreement.

Despite all these complex laws, mid-flight births are exceedingly rare—so rare, in fact, that most airlines don’t even keep track of the number of babies born in the air. An expecting mother likely wouldn't even be able to get onto a flight in the first place, since many airlines have rules that prohibit women from flying after they've reached a certain point in their pregnancy.

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