Messier-20 Is Called The “Trifid Nebula” Because Of The Three Bright Lobes In The Lower Purple-coloured

Happy Halloween, everyone!

2024 October 27

LDN 43: The Cosmic Bat Nebula Credit & Copyright: Mark Hanson and Mike Selby; Text: Michelle Thaller (NASA’s GSFC)

Explanation: What is the most spook-tacular nebula in the galaxy? One contender is LDN 43, which bears an astonishing resemblance to a vast cosmic bat flying amongst the stars on a dark Halloween night. Located about 1400 light years away in the constellation Ophiuchus, this molecular cloud is dense enough to block light not only from background stars, but from wisps of gas lit up by the nearby reflection nebula LBN 7. Far from being a harbinger of death, this 12-light year-long filament of gas and dust is actually a stellar nursery. Glowing with eerie light, the bat is lit up from inside by dense gaseous knots that have just formed young stars.

∞ Source: apod.nasa.gov/apod/ap241027.html

Mosaic of the Eagle Nebula, June 6, 2015. Image Credit: Adam Gustafson | Jamie Kern | BSU Observatory.

Imaged in luminance and photometric R, V and B filters. Approximately 2 hours total exposure time.

The Eagle nebula is a stellar nursery where new stars are born. 

Interacting galaxy

Interacting galaxies (colliding galaxies) are galaxies whose gravitational fields result in a disturbance of one another. An example of a minor interaction is a satellite galaxy’s disturbing the primary galaxy’s spiral arms. An example of a major interaction is a galactic collision, which may lead to a galaxy merger.

A giant galaxy interacting with its satellites is common. A satellite’s gravity could attract one of the primary’s spiral arms, or the secondary satellite’s path could coincide with the position of the primary satellite’s and so would dive into the primary galaxy (the Sagittarius Dwarf Elliptical Galaxy into the Milky Way being an example of the latter). That can possibly trigger a small amount of star formation. Such orphaned clusters of stars were sometimes referred to as “blue blobs” before they were recognized as stars.

Colliding galaxies are common during galaxy evolution. The extremely tenuous distribution of matter in galaxies means these are not collisions in the traditional sense of the word, but rather gravitational interactions.

Colliding may lead to merging if two galaxies collide and do not have enough momentum to continue traveling after the collision. In that case, they fall back into each other and eventually merge into one galaxy after many passes through each other. If one of the colliding galaxies is much larger than the other, it will remain largely intact after the merger. The larger galaxy will look much the same, while the smaller galaxy will be stripped apart and become part of the larger galaxy. When galaxies pass through each other, unlike during mergers, they largely retain their material and shape after the pass.

Galactic collisions are now frequently simulated on computers, which use realistic physics principles, including the simulation of gravitational forces, gas dissipation phenomena, star formation, and feedback. Dynamical friction slows the relative motion galaxy pairs, which may possibly merge at some point, according to the initial relative energy of the orbits.

Astronomers have estimated the Milky Way galaxy, will collide with the Andromeda galaxy in about 4.5 billion years. It is thought that the two spiral galaxies will eventually merge to become an elliptical galaxy or perhaps a large disk galaxy.

Source

Image credit: NASA/ESA & Hubble (procesed by:  Steve Byrne & Judy Schmidt)

Animation

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Every February 2, we wonder if Punxsutawney Phil will see his shadow.

In Saturn’s case, astronomers know some of Saturn’s moons will cast shadows across the planet’s iconic rings every 15 years. This effect only occurs when the planet’s rings are perpendicular to the Sun. The next time this will happen is in May 2025.

Watch as four of Saturn’s moons orbit the planet, based on images taken by the Hubble Space Telescope over a 9.5-hour span in 1995. Enceladus is first and Mimas is close behind. Both of these moons cast small shadows on Saturn, but among the two, only Enceladus’ shadow cuts across the rings. Dione follows next and casts a long shadow across the planet’s rings. About 12 seconds in, the moon Tethys moves swiftly behind the planet toward the right.

Credit: NASA/ESA/STScI.

We had an error on here earlier - fixed now.

Public nights are here!

Today's word of the day is "earthshine" which is when the Earth reflects the Sun's light so that it makes the dark side of the moon glow! Super cool.

Image credit: Abhijit Juvekar

The brown dwarf W1935 is a bit of a mystery. Astronomers using the James Webb Space Telescope picked up glowing methane—a sign that the object’s upper atmosphere is being heated. But the brown dwarf has no host star, so where could the heat be coming from?

In our solar system, Jupiter and Saturn show methane emission due to the presence of auroras—what we call the Northern Lights on Earth. W1935 might also have auroras, which could be powered by energetic particles from a nearby, active moon, like Jupiter’s Io: https://webbtelescope.pub/4aKMkBF

2023 September 18

The Red Sprite and the Tree Credit & Copyright: Maxime Villaeys

Explanation: The sprite and tree could hardly be more different. To start, the red sprite is an unusual form of lightning, while the tree is a common plant. The sprite is far away – high in Earth’s atmosphere, while the tree is nearby – only about a football field away. The sprite is fast – electrons streaming up and down at near light’s speed, while the tree is slow – wood anchored to the ground. The sprite is bright – lighting up the sky, while the tree is dim – shining mostly by reflected light. The sprite was fleeting – lasting only a small fraction of a second, while the tree is durable – living now for many years. Both however, when captured together, appear oddly similar in this featured composite image captured early this month in France as a thunderstorm passed over mountains of the Atlantic Pyrenees.

∞ Source: apod.nasa.gov/apod/ap230918.html