#AstroMiniBR: How do we know the shape of the Milky Way?

Every week, TecMundo and #AstroMiniBR bring together five relevant and entertaining astronomical curiosities produced by the world’s collaborators. twitter profile To spread the knowledge of this science, which is the oldest!

#1: A cosmic painting

This image looks like it came out of a dream, but clouds of gas found in a neighboring galaxy, the Large Magellanic Cloud.

The different colors in the clouds indicate the presence of chemical elements such as Hydrogen, Oxygen and Sulfur.#AstroMiniBR
{c} Team Ciel Austral pic.twitter.com/G1RkiPEI2W

— yanna martins franco (@martins_yanna) April 5, 2023

The above image shows one of the most famous and beautiful objects in the southern sky: The Large Magellanic Cloud, the largest moon in the Milky Way, is about 15,000 light-years in diameter and just 160,000 light-years away. Dorado constellation.

In fact, this recording makes for an even more special image because it goes beyond what is possible to see with ordinary visible light, captured by our eyes and our homemade telescopes. Covering a sky size equivalent to 10 full moons, this mosaic was created from an observation with a total exposure time of 1060 hours in both broadband and narrowband filters.

These filters are designed to transmit only the light emitted by sulfur, hydrogen and oxygen atoms, which are ionized by starlight and emit their characteristic light. As a result, in this image, the Big Cloud appears to be covered by a multitude of small clouds surrounding massive young stars!

#2: Hyper Speeds in Space!

What happens when small pieces of debris collide with probes and satellites in space?

These images show the results of impact tests between small pieces of plastic and aluminum at speeds of 25,000 km/h against metal blocks!
#AstroMiniBR

(c) ESA pic.twitter.com/sUW032neCl

— Nicolas Oliveira (@nicooliveira_) April 4, 2023

Outside the Earth’s atmosphere, artificial space debris and natural meteorites moving at high speeds can seriously damage satellites and pose a serious hazard to space flights, especially for manned missions. If a spacecraft collides with an object that has a relative velocity greater than the speed of sound in solid matter (about 4 to 5 kilometers per second or more than 20,000 kilometers per hour), this event is called a hypervelocity impact.

When an object hits a satellite or probe at these velocities, the result depends primarily on which piece was hit, the relative size of the target, and the size of the object hitting, in this case the “bullet”. As seen in the images above, the damage caused by the impact of plastic and aluminum pieces smaller than 3 cm can be irreversible. Unfortunately, only larger space objects can be more easily cataloged and tracked, so today only in these situations can collision be avoided through active countermeasures and/or evasive maneuvers.

#3: How do we know what the Milky Way looks like?

Can you take a picture of our galaxy while you’re in it? NO!
but we have good guesses of what it’s been like since 1785!

Picture 1 is by William Herschell, made by counting the little stars in the sky. Picture 2 is a nice detailed diagram of the spiral arms of the Milky Way.#AstroMiniBR pic.twitter.com/xWO5PYaOur

— yanna martins franco (@martins_yanna) April 8, 2023

If we’ve never left the Solar System, how do we know what our galaxy looks like? While this is an indisputable fact, so is the fact that man is a resourceful creature.

Since astronomers discovered the existence of other galaxies in the 1920s, significant advances have been made in understanding how the Milky Way formed and evolved over time. By mapping the distribution of stars, dust, and gas in our galaxy, it is possible to compare these data with observed images of other galaxies like ours, namely spiral galaxies.

Thus, it is possible to construct computational models that preserve the true physical properties of our galactic system and create a reliable picture of what it will look like from the outside.

#4: International Space Station Above the Sun

This AMAZING image @AJamesMcCarthy and shows different structures in the solar photosphere.

Dark areas are sunspots, regions of intense magnetic activity.
We see that the transit of the International Space Station (ISS) was also recorded! ????#AstroMiniBR pic.twitter.com/tHykw0iZ93

— Patricia Cruz, PhD (@patyccruz2) April 5, 2023

What is the sunspot and the human laboratory in this image? One such false spot is the International Space Station (ISS), seen passing in front of the Sun. Individually, sunspots have a dark central shadow and a lighter surrounding partial shade.

However, since the ISS orbits Earth in about 90 minutes, the transit of the Sun is not a very unusual event for those observing from the planet’s surface. This image is the result of combining observations of the Sun’s surface obtained by three telescopes: a hydrogen-alpha telescope to capture the Sun’s chromosphere in detail, and two telescopes with full-aperture solar filters to capture the ISS’s crossing against the sun. photosphere.

#5: What makes the sky blue?

Is it because the sky is blue?

The answer lies in Rayleigh scattering. this effect shows that molecules in our atmosphere “deflect” the blue part of sunlight more efficiently* #AstroMiniBR
{c} ISS/NASA

* sunlight is white -> consists of all colors ?? pic.twitter.com/ftYPJcOaVv

— yanna martins franco (@martins_yanna) April 10, 2023

Have you ever wondered or been asked by a child at some point in your life: why is the sky blue? The answer to this classic question is simple: Like energy passing through the ocean, light energy travels in waves. Some of the light travels in short, “squiggly” waves, while other light travels in long, lazy waves.

Blue light waves are shorter than red light waves. Sunlight hits the Earth’s atmosphere and is scattered in all directions by all the gases and particles in the air, and in the process, blue light is scattered more than any other color. That’s why we see a blue sky (most of the time!).