Beyond the Limits of Earth – Astrophotography from an Airplane

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When I was back to Lisbon from a large trip between Chile, Argentina and Uruguay with a stopover in São Paulo, Brazil, I had a rare opportunity somewhere in the middle of the Atlantic Ocean and under the moonlight to take some images from the window of an airplane, during the sleeping hours, when the lights of the plane were shut off. I asked my colleague Apolónia Rodrigues to cover my head with a black jacket around the window to avoid any reflections from inside. The shutter speed had to be very fast for a night sky photography because it was very difficult to have a pinpoint stars without shaking with the movements of the plane. After a few attempts and efforts, I could capture some nice views with the stars and the night sky above Earth taken at a high altitude, probably between 10,000 to 12,000 meters at a cruise speed of ~900km/h, some of them with lightning below.

Due to the presence of moonlight we can distinguish very well the limb and transition between the blue color from our atmosphere and the black from outer space. Blue light is scattered more than other wavelengths by the gases in the atmosphere, giving Earth a blue halo. The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth’s gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation). The atmosphere has a mass of about 5.15×1018 kg, three quarters of which is within about 11 km (6.8 mi; 36,000 ft) of the surface. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. The Kármán line, at 100 km (62 mi), or 1.57% of Earth’s radius, is often used as the border between the atmosphere and outer space.

PT: De regresso a Lisboa a partir de uma grande viagem entre o Chile, Argentina e Uruguai com escala em São Paulo, Brasil, eu tive uma oportunidade rara enquanto estava algures a sobrevoar o Oceano Atlântico, de captar imagens ao luar a partir da janela de um avião comercial, durante as horas de sono e enquanto as luzes do avião foram desligados. Pedi à minha colega de equipa Apolónia Rodrigues para me cobrir a cabeça e ao redor da janela com um casaco preto, no sentido de evitar quaisquer reflexos a partir do interior do avião. A velocidade do obturador tinha que ser muito rápida para uma fotografia de céu noturna, porque era muito difícil ter estrelas pontuais com a agitação do avião. Depois de algumas tentativas e esforços, tive a felicidade de captar algumas imagens com as estrelas pontuais onde se distinguem as estrelas que compõem o Cão Maior e Orion e onde é possível ver também o contorno da atmosfera acima da Terra. As imagens foram tiradas a uma alta altitude, provavelmente entre 10.000 a 12.000 metros e a uma velocidade de cruzeiro de ~ 900 km/h, alguns deles com relâmpagos abaixo .

The troposphere is the lowest layer of Earth’s atmosphere. It extends from Earth’s surface to an average height of about 12 km, although this altitude actually varies from about 9 km (30,000 ft) at the poles to 17 km (56,000 ft) at the equator, with some variation due to weather. Most conventional aviation activity takes place in the troposphere, and it is the only layer that can be accessed by propeller-driven aircraft.

In one of the pictures I made an annotation with the main constellations visible. Orion and Sirius are very well spotted. Each one is a single shot: Canon 6D, Exp: 1/3s; ISO8000 24mm f/2.8


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