Here I collect, so to speak, the ‘FAQ’ from my years of experience as a ‘communications officer’ and ‘muse’ of astronomy.

Why do we see the moon as a crescent, like a boat, in the Arab world?

Let’s first consider the horizons of the two observation points: A (yellow) is a location in the Arab world, B (green) is a location in Europe (e.g. Berlin). Looking at the Earth from outside, the horizon of each location would be a tangential surface at that point.

The figure shows the scenario ‘cut open’, i.e. in 2D.
It is easy to see that the horizons of A and B intersect the equator of the sky and the earth at different angles. This angle is 90° minus the geographical latitude of the location.
Conversely, the height of the celestial pole above the local horizon is then, of course, exactly the geographical latitude. The pole is therefore located at A alpha degrees above the horizon.

If we consider the height of the rotational pole above the horizon in the horizon system of any location, the following picture emerges for points A and B on Earth:

In the Arab world, the celestial pole is lower above the horizon. However, the celestial pole is precisely the point around which all celestial bodies appear to move during the course of the day. The path of a celestial body – be it a star or our moon – is therefore flatter above the horizon in Berlin (left image) and steeper in the Arab world (e.g. southern Sahara, right).

We can visualise this with a bucket:

We consider its handle to be the moon’s path in the sky and stick a banana peel to the handle to represent the crescent moon. The edge of the bucket is our local horizon. If we now compare two views from different locations on Earth, it is as if we were tilting the handle at different angles.

Try this experiment and explain why the Islamic crescent moon is positioned as it is!

All clear?

The Bucket/ Teapot Experiment

We can see that

if we choose an observation point further north or south on Earth, i.e. at a higher northern or southern latitude, the banana peel is more or less perpendicular to the edge of the bucket, i.e. to the local horizon.

However, if we choose a location near the equator, i.e. with a flatter lunar orbit, the crescent moon appears to lie more on the horizon, like a boat.

Zodiac

Why can’t I see my zodiac sign in the sky on my birthday?

Over the course of a year, the Earth orbits the Sun. So, from our perspective on Earth (geocentric), it appears as though the Sun is travelling once around the entire celestial sphere.

So what is a zodiac sign?

According to ancient astrology, the zodiac sign that the Sun is in on your birthday is called your birth sign.

Task: Using the following image, explain when the region of the sky where your birth sign is located can be seen in the night sky:

Please note: Constellations are sections of the ecliptic (see Wikipedia) that in most cases no longer correspond to the constellations of the same name.

VEGA Introduction to Stellarium (German)

Here is a link to ESA – Celestial Globe Icosahedron with HIPPARCOS data.
//youtube.com/watch?v=fB7NkExZlHk&feature=youtu.be

VEGA Planet Puzzle

In a planet game, you can learn about our solar system in a fun way.

Task 1: Puzzle the planets!

Task 2: Research the characteristics of the planets and their distances from the Sun on the Internet!

Task 3: Write profiles for the planets and think about what life on such a planet would be like.

  1. Compare the planets with Earth.
  2. Is there (enough) oxygen there, and could humans breathe?
  3. Is the atmosphere dense enough, or perhaps too dense? Is there water, and could plants live there (breathing CO2)?

Task 4: Build a planetary path… either on the ceiling of your room (the lamp is the sun) or in the schoolyard.

Here is a planetary path that was built and inaugurated as part of the German-Russian youth exchange I initiated. 🙂