Amid the Stars

From Earth, comets look like a dazzling trail of light in the sky. Looking up close gives you a whole different perspective. This is the surface of Comet 67P/Churyumov-Gerasimenko, as seen by the Rosetta spacecraft, a probe sent to study the comet up close in 2014. (1/3) #Astronomy ⚛️🧪🛰️

Rosetta's lander was the first spacecraft to land on the surface of a comet. Comets are made of a mixture of ice and dust, lending them the nickname of dirty snowballs. They even look like one up close. Captured in this photo is a plume erupting out from the comet's surface. (2/3) 🔭⚛️🧪🛰️

On Saturn's moon Titan, you'd be able to fly, simply by tying fake wings to your arms and flapping. Titan is the only moon in our Solar System with a dense atmosphere. It's about 50% denser than Earth's. It also has gravity that's only about 14% of Earth's. (1/2) #Astronomy ⚛️🧪🛰️

This dazzling shot from Webb shows us the Westerlund 2 star cluster within the nebula Gum 29. This tightly packed cluster hosts some of the brightest, hottest, and most massive stars in the Milky Way. (1/3) #Astronomy ⚛️🧪🛰️

This is an example of a stellar nursery, a nebula cloud where stars are actively forming. The distribution of the stars relative to the shapes and colors in the cloud gives us insights into the dynamics of star formation. (2/3) 🔭⚛️🧪🛰️

This was the first rocket launch at Cape Canaveral. Cape Canaveral is the home of the Cape Canaveral Space Fore Station and next to the Kennedy Space Center, making it the US capital of rocket launches. But every legacy had to start somewhere. (1/3) #WorldSpaceWeek #RocketRevolution #Astronomy ⚛️🧪🛰️

This rocket was a Bumper V-2, a hybrid of the German V-2 and the American WAC Corporal as an experiment with 2-stage rockets. Today, all rockets launched to space are multistage, so this test left a lasting legacy. The upper stage made it to a then record-breaking altitude of 400 km. (2/3) 🔭⚛️🧪🛰️

For 2.5 minutes, a Saturn V rocket nearly matched the output of the entire U.S. power grid. (1/2) #WorldSpaceWeek #RocketRevolution #Astronomy ⚛️🧪🛰️

Gamma-Ray Bursts are the most energetic events, short of the Big Bang, we know of. In less than 10 seconds, a gamma-ray burst will release more energy than the Sun will across its entire 10-billion year life span. (1/3) #Astronomy ⚛️🧪🛰️

Gamma-ray bursts are believed to occur during the supernovae of extremely massive stars as they collapse into neutron stars or black holes. Jets of gamma rays are launched from the poles. One pointed at Earth in our galaxy, even at the opposite end, would cause a mass extinction. (2/3) 🔭⚛️🧪🛰️

The arc seen here within the Orion Nebula is an example of a bow shock, created when the stellar wind from the nearby young variable star, LL Orionis, collides with the slower moving gas of the nebula cloud. (1/3) #Astronomy ⚛️🧪🛰️

The arc shape is a bow shock, which occurs when areas of two different pressures and/or densities collide. It is essentially the same thing as the wave that surrounds a ship moving through water. Alternatively, the sonic boom heard from a supersonic aircraft is another example. (2/3) 🔭⚛️🧪🛰️

This is M77, the Squid Galaxy, as seen by Webb. The bright orange light at its center is an example of an active galactic nucleus (AGN), with the large arms coming off it being diffraction spikes due to its intense brightness. (1/3) #Astronomy ⚛️🧪🛰️

Galaxies tend to have a black hole at their center. If the black hole has an accretion disk, an orbiting ring of material, the accreting gas and dust is moving so fast that there's a lot of friction, and friction creates heat and light. This is what causes AGN to glow intensely. (2/3) 🔭⚛️🧪🛰️

Mars' sky is the opposite of Earth's. It's red during the day, but blue at sunset. We often like to look at the similarities between Earth and Mars, but this is one interesting way that things are different. (1/3) #Astronomy ⚛️🧪🛰️

Earth's blue sky is due to gas molecules in our atmosphere that scatter blue light in all directions more so than other colors. But at sunset light has to travel at a steeper angle, and therefore through more air, meaning all the blue light has been scattered away before reaching you. (2/3) 🔭⚛️🧪🛰️

What is up with this galaxy? NGC 474 is a elliptical galaxy. Rather than the spiral shape we're used to, an elliptical galaxy takes a round shape. This one in particular features several layers of shells, and we don't fully understand what causes them. (1/2) #Astronomy ⚛️🧪🛰️

This is NGC 346, an open star cluster in a nebula. Stars are born in large numbers inside of a nebula, resulting in an open cluster, a group of thousands of stars loosely bound together by their mutual gravity. They're like the children who aren't old enough to move out. (1/3) #Astronomy ⚛️🧪🛰️

An open star cluster is not permanent. The stars are not tightly packed enough for their gravity to completely overcome their velocity. After millions of years, a rather short amount of time in the lifespan of a star, the stars will go their separate ways and move out of the house. (2/3) 🔭⚛️🧪🛰️

From Earth, any observation of Saturn will only see its day time side, as when the planet is on the night side of Earth, it's opposite from the Sun, leaving the Sun-facing side also facing Earth. But this observation from the Cassini probe shows a crescent Saturn. (1/2) #Astronomy ⚛️🧪🛰️