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.

Turn Your LEGO Bricks Into a Drone With the Flybrix Drone Kit

Flyxbrix/FatBrain
Flyxbrix/FatBrain

Now more than ever, it’s important to have a good hobby. Of course, a lot of people—maybe even you—have been obsessed with learning TikTok dances and baking sourdough bread for the last few months, but those hobbies can wear out their welcome pretty fast. So if you or someone you love is looking for something that’s a little more intellectually stimulating, you need to check out the Flybrix LEGO drone kit from Fat Brain Toys.

What is a Flybrix LEGO Drone Kit?

The Flybrix drone kit lets you build your own drones out of LEGO bricks and fly them around your house using your smartphone as a remote control (via Bluetooth). The kit itself comes with absolutely everything you need to start flying almost immediately, including a bag of 56-plus LEGO bricks, a LEGO figure pilot, eight quick-connect motors, eight propellers, a propeller wrench, a pre-programmed Flybrix flight board PCB, a USB data cord, a LiPo battery, and a USB LiPo battery charger. All you’ll have to do is download the Flybrix Configuration Software, the Bluetooth Flight Control App, and access online instructions and tutorials.

Experiment with your own designs.

The Flybrix LEGO drone kit is specifically designed to promote exploration and experimentation. All the components are tough and can totally withstand a few crash landings, so you can build and rebuild your own drones until you come up with the perfect design. Then you can do it all again. Try different motor arrangements, add your own LEGO bricks, experiment with different shapes—this kit is a wannabe engineer’s dream.

For the more advanced STEM learners out there, Flybrix lets you experiment with coding and block-based coding. It uses an arduino-based hackable circuit board, and the Flybrix app has advanced features that let you try your hand at software design.

Who is the Flybrix LEGO Drone Kit for?

Flybrix is a really fun way to introduce a number of core STEM concepts, which makes it ideal for kids—and technically, that’s who it was designed for. But because engineering and coding can get a little complicated, the recommended age for independent experimentation is 13 and up. However, kids younger than 13 can certainly work on Flybrix drones with the help of their parents. In fact, it actually makes a fantastic family hobby.

Ready to start building your own LEGO drones? Click here to order your Flybrix kit today for $198.

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What Is the Insurrection Act?

The Insurrection Act gives the president the authority to address domestic disturbances using the military.
The Insurrection Act gives the president the authority to address domestic disturbances using the military.
Tero Vesalainen/iStock via Getty Images

The use of military forces to address volatile situations normally under the purview of law enforcement within the United States is a very rare occurrence, and for good reason. Troops are legally forbidden to be involved in domestic law enforcement affairs without prior congressional authorization.

One loophole does exist. It’s the Insurrection Act, and it empowers the president to dispatch soldiers to combat an insurrection, civil disturbance, natural disaster, or terrorist attack on American soil. But actually invoking the Insurrection Act is no simple matter.

The Act was introduced in 1807 and gives the president the authority to direct American troops to intervene in state-level civil unrest in the event local authorities are unable to control the disturbance. (It was amended in 2006 following Hurricane Katrina to include disasters and terrorism.) It’s used sparingly, particularly as modern police forces have become more militarized. The last time the Act was invoked was in 1992, when riots following the acquittal of four police officers tried in the beating of Rodney King consumed Los Angeles.

At the time, the California governor requested military forces—and normally, the president would activate federal troops at the behest of a governor or state legislature. According to the Los Angeles Times, one exception for dispatching soldiers without state approval is an indication that states are violating civil rights, as was the case for several U.S. presidents (Dwight Eisenhower, John F. Kennedy, and Lyndon B. Johnson) who used military forces to back desegregation in Southern states. Alternately, the president would have to believe such events are interfering with a state’s ability to enforce their laws.

Put simply: Military forces are typically sent at the request of the state, but a request isn’t necessary if the president believes troops are needed to restore order.

When states believe local police are being overwhelmed, their preference is to use the National Guard, which is authorized to act as law enforcement on domestic soil.

If the Act is used, the president would first have to issue a proclamation ordering those involved in any disturbance to disperse. If that fails, the president would issue an executive order to activate the military. States would then likely argue against the intrusion of such forces. It is not clear, however, that they would have the legal justification to prevent such an action if the president calls for it.

[h/t Los Angeles Times]