Monthly Archives: January 2019

What is Jacob’s Ladder?

If you’ve taken our Electricity and Magnetism class, you’ve seen this device before! You press a button and an electric arc rises to the top of two tall wires. This is the Jacob’s Ladder! But what’s happening here? 

Jacob's Ladder

The base of the Ladder is a transformer — a device that changes an incoming voltage. In the Ladder’s case, it increases it by a huge amount. That voltage is put into one of the vertical wires, increasing its electric potential. The electricity needs to flow somewhere, so it ionizes the air to jump to the other vertical wire. As the electricity arcs, it heats up the ionized air, which causes it to rise. As the wire get further apart, it becomes more and more difficult for the electricity to reach, and the arc eventually stops. Then the transformer builds up the electric potential again, repeating the process all over again. Though as electricity flows through the wires, they heat up. The hotter they are, the slower the electricity flows. Eventually, you’ll notice the arc having trouble getting to the top as it travels slower and slower.

Jacob's Ladder 2

This is just one of the many cool electricity demos we have at AstroCamp! Be sure to check out this and all the others on your trip.

Written By: Scott Yarbrough


Measuring the Brightness of Stars

There are countless stars that we can see in our night sky, and all of them are unique. Some are dim, barely visible without a telescope. Others are bright and can be seen even in the most light-polluted areas. We measure the brightness of these stars using the magnitude scale.

brightness of stars

The magnitude scale seems a little backwards. The lower the number, the brighter the object is; and the higher the number, the dimmer it is. This scale is logarithmic and set so that every 5 steps up equals a 100 times decrease in brightness. So magnitude 10 is 100 times dimmer than magnitude 5, which is 100 times dimmer than magnitude 0.

brightness of stars scale

Our sun — the brightest thing in our sky — is magnitude -26.7. Other objects like the moon or nearby planets have negative magnitudes, and other stars vary greatly. The dimmest objects humans can see with the naked eye is around 6; any dimmer and we need to use a telescope.

What we’ve been talking about is apparent magnitude. It measures the brightness of stars and other celestial objects as they are as viewed from Earth, without taking into account distance or actual luminosity. It’s fine for describing what things look like from here, but it isn’t very good at describing how much light those objects are actually emitting. Our moon is incredibly bright to us, but if it were farther away from us, its brightness would decrease a lot.

To better compare the brightness of objects to each other, we use the absolute magnitude scale. The logarithmic scale is the same, but we calculate what an object’s apparent magnitude would be if it were exactly 10 parsecs away from Earth (about 33 light-years away). This way, we eliminate distance as a factor for comparing the brightness of space objects.

brightness of stars gif

As you can see, the brightness measurement of stars is a little more complicated than it first appears. It may also be difficult to really visualize the difference in brightness. But it’s an easy task to find a catalog of stars, go outside, and experience it yourself!

Written By: Scott Yarbrough

What in the World is a Super Blood Wolf Moon?

On January 20, around 8.30 PST, the Earth is going to pass directly between the moon and the sun. This is normally the time when the moon would be full, reflecting the sun’s rays back to us on Earth with all of the side facing towards us. But the Earth’s shadow is going to fall across the moon’s surface, giving us a SUPER BLOOD WOLF MOON.

super blood wolf moon

This is a silly name, we can all agree on that. But more than just being a ridiculous sequence of words, the Super Blood Wolf Moon combines several colloquial names in a strange but accurate way. The word “Super” comes from the term “super moon,” a phenomenon where the full moon occurs at the same time as the moon’s closest approach to Earth. The moon appears slightly larger during this time, though not by much. “Blood” comes from the reddish color the moon becomes during the lunar eclipse as red and orange light gets refracted through the Earth’s atmosphere as it travels towards the moon. “Wolf” is an old name for January’s full moon, coming from Native American tradition. Each other month has a name for its full moon, too!

super blood wolf moon 1

So there you have it. Super Blood Wolf Moon definitely isn’t a made-up thing, and though your friends and family won’t believe you when you tell them about it, it’s going to be an incredible event that you won’t want to miss!

Written By: Scott Yarbrough



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