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Galaxy M74

From NASA via Astronomy Picture of the Day for 13/8/21.

A beautiful spiral galaxy. The image shows emissions from hydrogen atoms, emphasising the reddish glow of the parts of the galaxy where stars are forming.

Galaxy M74

The galaxy looks slightly different in visible light.

Fire in Free-Fall

Fire is an odd, complicated chemical phenomenon. When in orbit round Earth it becomes even odder.

In a gravity well gravity shapes the flame to the familiar cone-like contours we can see flickering, ushering oxygen to the bottom of the fire, the product gases rising from the flame due to their lower density.

In orbit, when bodies are in free-fall (not “weightless”: the gravity is still there, only cancelled out by forward movement round the Earth, the link calls that situation microgravity) there is no bottom to the flame; oxygen is attracted from all sides and the fire becomes spherical.

Thsi image is from Astronomy Picture of the Day for 10/8/21.

Fire in space

I wouldn’t have liked to try that out, even if it is in a controlled environment. Fire in a spaceship must be like one on a sea-going vessel; the crew’s worst nightmare.

Ring Galaxy AM 0644-741

This lovely picture comes from NASA via the Hubble Telescope and Astronomy Picture of the Day for 28/7/21. The galaxy’s distorted shape is due to it having interacted with another galaxy (top right) which passed through it.

Ring Galaxy AM 0644-741

Andromeda in Ultra-violet

This is from NASA via Astronomy Picture of the Day for 18/7/21.

The Andromeda Galaxy as seen in ultra-violet light. Compared to visible light images it really picks out the spiral arms but makes them look more like rings.

Andromeda in u-v

A Celestial Necklace

From Astronomy Picture of the Day for 18/5/21.

This beautiful celestial apparition is known as the Necklace Nebula. It is a so-called planetary nebula. These are formed by gases thrown off by stars nearing the end of their lives. The Nebula Necklace’s “Diamonds” are knots of glowing gas.

The Necklace Nebula

Crescent of Earth

Only 24 people have ever had the chance to see a view like this – or photograph it. The 24 astronauts of the Apollo Programme who made it to the Moon and back.

From Astronomy Picture of the Day for 29/4/21, a digitally restored photograph of the whole of planet Earth from its nightside, the last picture of its kind so far to be taken by human hands.

Crescent of Earth

Star Shredding Animation

From You Tube via Astronomy Picture of the Day for 27/4/21.

An animation of a star being shredded by a black hole.

Ingenuity’s First Flight.

From You Tube via Astronomy Picture of the Day for 20/4/21.

Ingenuity’s first (short) flight through the Martian atmosphere as seen from the Perseverance rover.

Eyeball this Nebula

I found this (copyrighted) image on Astronomy Picture of the Day for 18/1/21.

The text on APOD’s post refers to it as looking like a brain – hence its name, the Medulla Nebula.

To me, though, it looks more like an eyeball – with the optic nerve going off to the right as in the diagram below.


Mountains on Pluto

Remember those days when Pluto was just a blip on a photographic plate, then merely a fuzzy set of dots on a Hubble telescope image?

No more.

Astronomy Picture of the Day for 15/1/21 featured this photo taken by the New Horizons probe 15 minutes after its closest approach to the (dwarf) planet when it was 18,000 kilometres away from the surface.

Some of the mountains on show are comparable in height to the highest on Earth but of course they are not composed of rock but most likely of ice. The plains below them may contain solid nitrogen or carbon dioxide.

Also visible above Pluto’s horizon is its tenuous atmosphere.

Pluto's Mountains

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