Two commercial airline pilots saw a light 150km away that was still then suddenly accelerated at incredible speed and disappeared

I was flying 37,000 feet above Baku and could see directly in front the Caspian Sea. It was night time very early in the morning (13 Zulu). My Co-pilot said look over there. It was 10 degrees below the horizon. I started to make some calculations to understand where in elevation it was. It looked like bright planet but it was 10x times the size of the planet. The light started to descend and then moved 20 degrees above the horizon. Then it took off at an incredible speed going towards Kazakstan. This was definitely not the orbital station because it was way faster. It was probably 150 km in front of us.