Orion’s belt runs just along the horizon, seen through Earth’s atmosphere and rising in this starry snapshot from low Earth orbit on board the International Space Station. The belt stars, Alnitak, Alnilam, and Mintaka run right to left and Orion’s sword, home to the great Orion Nebula, hangs above his belt, an orientation unfamiliar to denizens of the planet’s northern hemisphere. That puts bright star Rigel, at the foot of Orion, still higher above Orion’s belt. Of course the brightest celestial beacon in the frame is Sirius, alpha star of the constellation Canis Major. The station’s Destiny Laboratory module is in the foreground at the top right.
Image credit: NASA, ISS Expedition 40, Reid Wiseman
The size of North America compared to the Great Red Spot on Jupiter.
Great Red Spot, an enormous, long-lived storm system on the planet Jupiter and the most conspicuous feature of its visible cloud surface. It is generally reddish in colour and oval in shape, approximately 20,000 km long and 12,000 km wide (12,400 by 7,500 miles)—large enough to engulf Earth and Mars side by side.
This diagram shows our cosmic address at a glance. We see our planetary system around the Sun, our stellar neighborhood in our galaxy, our galaxy in the local group of galaxies, and our group in the entire universe.
Scientists have theorized that our Milky Way galaxy has a super massive black hole at the center of it, but how did this idea come about? How do astronomers measure something that has actually never been seen in our telescopes?
Above is an animation of star movements in our galaxy over the past 16 years. They all orbit around a point that emits no light in our galaxy. We can measure the mass of these stars and calculate that their orbits require an object with the mass of 4 million Suns. So far this points to a super massive black hole in our galaxy.