Caption: 國際天文學聯合會 OAE 天文攝影比賽星軌類第三名。 這張壯觀的圖片捕捉到了大自然最富戲劇性的表現形式--火山爆發和夜空。前景中的火山是埃特納火山，位於意大利西西里島，於 2021 年 2 月噴發。在背景中，我們可以看到地球繞假想軸轉動產生的星軌。由於埃特納火山位於北緯 37°左右，我們會注意到空中的弧線相當平緩，因為這裡遠離北極，從那裡看天空軌跡會呈現接近圓形的形狀。當我們從南半球或北半球向赤道移動時，星軌逐漸由圓形變為更加平行的線條，這是因為觀察者逐漸遠離指向地球自轉軸之一的天頂位置。因此，天空為我們提供了有關位置和時間的寶貴信息，也是古代文明追蹤天體運動的重要實踐。這幅圖像還捕捉到了恆星因溫度不同而產生的不同顏色：溫度較低的星為白色和紅色，而溫度較高的恆星更藍。
Credit: Dario Giannobile/IAU OAE

Caption: 國際天文學聯合會 OAE 天文攝影比賽星軌類第二名。 天文學即使不是最古老的科學，也是其中之一，因此千百年來與各種文化都有著千絲萬縷的聯繫。這張圖片以巨石陣為背景，在某種程度上傳達了這種聯繫。關於天文學家所說的考古天文學遺址，以及它們與天空的聯繫（如季節、月相等），有很多研究。古今中外的文明對天空中的景象都有自己的看法和解釋，這不僅與文化有關，也與人們的日常活動和季節活動有關。通常被稱為 "星軌 "的 "同心圓 "是天空視運動的結果，實際上是地球自轉的結果。圖像中心上方出現的小點是Polaris--北極星。只有北半球的觀測者才能看到北極星。北極星的高度可以用來推斷觀測者的實際緯度。巨石陣位於北緯 51°左右。這張照片攝於世界上最著名的古代遺址之一，它把我們帶回了過去，讓我們對千年前生活在那裡的人們所講述的故事產生了好奇。
Credit: Till Credner/IAU OAE

Caption: First place in the IAU OAE Astrophotography Contest, category Star trails. This star trail image shows the apparent movement of the stars in the night sky, which results from the Earth’s rotation around its polar axis. The trees in the foreground serve as an anchor as we turn with the Earth. The bright white semi-circle in the center of the image is the North (Pole) star – Polaris, which is located very close to the North Celestial Pole. One way to imagine that the Earth is at center of hollow crystal sphere, and the stars are embedded on this sphere, as the Earth spins on its axis, an observer on Earth sees the stars rising and setting, following an arc, because the horizon prevents the observer from the full arc for stars that are further away from the Celestial Pole. The North Celestial Pole (and its opposite the South Celestial Pole) is essentially formed by extending the line of the Earth’s axis. Capturing this image requires the photographer to take a long exposure with the camera on a tripod and pointing towards the Pole Star (North Hemisphere). In the Southern Hemisphere there is no star as close as Polaris is to the Celestial Pole, so the position of the South Celestial Pole is found using the South Cross and Pointer Stars (Alpha and Beta Centauri). Although overall the image has a slight blue tint, it does capture the varying colours of stars, it is easy to distinguish between the higher temperature blue stars and the lower temperature of the whitish stars, and even lower temperature reddish stars. The reason for this variation in colour is because higher temperature stars emit more in shorter wavelengths (bluer), compared to lower temperature stars which emit in longer wavelengths (redder).
Credit: Fabrizio Melandri/IAU OAE