Twinkle twinkle little star, how I wonder what you are! On a dark night away from the city, is there anything more wondrous than a sky full of twinkling stars? Stars appear to ‘twinkle’ due to astronomical scintillation. The different air densities in the constituent layers of the atmosphere act like giant lenses refracting light, creating the flickering effect as they move. Astronomers use adaptive optics to correct the distortion. Stars have many practical uses too, beyond romantic swooning. They have been used for night time navigation. The ‘Pole Star’ was the most critical for navigation in the northern hemisphere, being the star nearest the celestial north pole. Due to to movement of the stars over time the ‘Pole Star’ is not a fixed point. Currently Alpha Ursae Minoris is less than 1% from the closest possible point to the celestial pole.
When Jane Taylor first published the lullaby Twinkle twinkle little star in 1806 little was known about stars; “How I wonder what you are!” was a true sentiment. Advances in radio astronomy and space telescopes have unlocked many mysteries and raised even more. Now, our nearest star, the Sun (a ‘yellow dwarf’) is to be studied in detail by the Parker Solar Probe which will travel to within 6.6 million kilometres. Not impressed? Well, the nearest the planet Mercury comes to the Sun is 58 million Kilometres! So Parker is getting really close and studying some important issues, such as solar winds, flares and its magnetic field. Without our sun there would be no life on earth.
Ultimately, stars are the forge where elements are created. They are the furnaces of matter. The forces of nuclear fusion generate pressure and heat forcing lighter elements together to form heavier ones. The temperature of our own sun’s core is estimated to be 15 million degrees Celsius! Even on a star’s supernova death, elements are created. The energy released on the death of a star creates some of our rarest elements; uranium, gold and platinum. We are made from stars! Eternity is written in our very cells.
Christmas is a time to regain wonder. As the wise men followed the star to find Jesus, little did they know the objects they observed were millions of light years away, so far that the stars themselves may be a black holes by the time the light reaches earth. They did not know that the elements making the gold they carried were created in stars. As the wise men followed the star to find Jesus, they did know a fragile baby, who became a refugee, light in the darkness, a true north, life giving, God with us. May your light shine this Christmas!