Polaris and Constellations

The STEM challenge by the ICSE

ICSE – what exactly is that? It stands for International Center of STEM Education and it’s based at the University of Education in Freiburg, Germany. The ICSE is an internationally connected research center with a special focus in practice-related research and its transfer into practice. I know this, because I work at the MaSDiV project which is affiliated with the ICSE. I’ll come back to that in another post because today I want to talk about the STEM challenge, the ICSE posed on Twitter.

STEM challenge posed by the ICSE. A great starting point to talk about seasons, constellations and the axial tilt.

Ultimately, this challenge can be separated into two questions:

1. Why does the North Star (or Polaris) stay in place?
2. Why do different stars appear with the seasons?

So let’s talk about these two phenomenon and at the end I want to discuss an implementation into physics or science lessons.

It seems like the North Star does barely move.

Over the course of the night, all stars rotate, except for the North Star. Polaris seems to stay at one point. Earth’s movement around its axis is the reason the sun and the stars rise and set each day. We notice Polaris because it’s an exceptionally bright star. It can be easily found every night, mostly because of its unique characteristic of almost staying in the same place the whole night. But why is that so?

Polaris is an exception in the night sky. The axis of Earth is tilted with an angle. And since the North Star lies almost exactly above the Earth’s axis, it’s like the hub of a wheel. And I say almost because as you can see in the picture above, even the North Star wobbles a little over the course of the night.

The axial tilt of the earth is the reason why the North Star appears to stay at one point in the Northern Hemisphere night sky.

Now that we’ve talked about the axial tilt and its consequence of the North Star seemingly staying in place, let’s discuss why different stars appear with the seasons. And with this I would really like to make an example of two constellations – the Lyra and Orion. Constellations are groups of stars that form an imaginary pattern. From the northern hemisphere, the Lyra or Orion are well seen either during Summer or during winter.

Seasonal change of constellations.
Graphic by Classzone

The reason for the seasonal change of the constellations is the movement of Earth around the sun:
In Northern hemisphere’s Summer, the nightsky faces towards constellations like Lyra. While in Winter, the daytime side of Earth faces the part of the sky containing Lyra, while constellations like Orion are visible at night.

My conclusion for this STEM challenge is its great opportunity to reflect on a phenomenon I grew up with. Real-life contexts need to be broken down into smaller questions, which is shown very well with this example.

I love the potential in this challenge. A lot of astronomy can be covered and explore going from here. For example, the formation of the seasons can be explored, since students already know about the axial tilt. With balls or oranges, this can even be transformed into hands-on, investigative activities. Students can directly transform their everyday observations and connect it to the content. I believe this is the core of great physics or science lessons because it makes the content instantly relevant for students. This could lead to a huge gain in motivation.

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