Cosmic Father's Day

Cosmic Father's Day
IC 4628, nicknamed the Prawn Nebula, an emission nebula in the constellation Scorpius. [Credit: ESO, acknowledgement: Martin Pugh]

Father's Day is celebrated on or near the June solstice in most English-speaking countries. Two major exceptions are Australia and New Zealand, where it takes place on the first Sunday of spring. But Father's Day isn't an astronomical holiday. The English-speaking tradition began in the USA as a counterpart to Mother's Day, and its nearness to the solstice is incidental. It has different dates and origins in many other countries.

It's common to have cards and other items saying “World's Best Dad”, a meal out, maybe something related to a favorite sport and – of course – a tie. The tie has become such a cliché that there are dozens of cartoons about it. But what might the cosmos have to offer to a cosmic father?

Cosmic edibles
For breakfast there is the Fried Egg Nebula (IRAS 17163-3907), which is 13,000 light years away in the constellation Scorpius. It's a probable yellow hypergiant star which has used up all of its hydrogen fuel, and been burning heavier elements. Heavier fuels produce more heat and make the star expand. From its outer layers it has expelled gases and dust, producing two huge shells of debris around it making it look a bit like a fried egg.

And if you have plenty of maple syrup and lots of time, the Pancake Galaxy (ESO 373-8) is 25 million light years away in the constellation Antlia. It's actually just a normal spiral galaxy, but since we see it edge-on, it looks flat.

The heavens have plenty of sea creatures, including the zodiac constellations Cancer (crab) and Pisces (fish). In addition, about 6000 light years away in the constellation Scorpius, is the Prawn Nebula (IC 4628), an emission nebula. A nebula is just gas and dust, so it doesn't shine. However if the hydrogen gas is energized by the radiation of a hot star, it emits a red glow.

Another emission nebula in Scorpius is the Lobster Nebula (NGC 6537), a stellar nursery containing some of the most massive stars ever discovered. It's full of protostars (stars in the process of forming), and also baby stars protected by thick gaseous cocoons.

Possibly the most famous heavenly crustacean is the Crab Nebula (M1), in the constellation Taurus. It reminded Lord Rosse of a crab when he saw it through his 36-inch telescope in 1840, though I can't see the resemblance. The well-known Hubble Space Telescope image certainly doesn't look crablike. It's what's left of a star that exploded as a supernova which was observed in 1054. At the center of the nebula is a pulsar, a pulsing neutron star.

The Fish on the Platter nebula is part of the Cygnus Star Cloud. Dark nebulae give it a look of . . . a fish on a platter. The nebulae are dark because of thick dust which is visible against a background of stars and emission nebulosity.

But maybe a good old-fashioned Hamburger Galaxy (NGC 3628) would do. This galaxy is edge-on to us and the dark dust lane in the middle makes it look a bit like something sandwiched between two buns.

Cosmic sports
And how about golf? Alan Shepard, commander of Apollo 14, made two impressive golf shots on the Moon. Astrophysicist Ethan Siegel has calculated that you could hit a golf ball nearly two and a half miles (over 3900 meters) on the Moon, and it would take over a minute to land. But you'd need a pretty big golf course.

Swimmers would be disappointed with any planet other than Earth. The only other body in the Solar System with surface lakes is Saturn's moon Titan, and its lakes are liquid methane, so not recommended. But for ice skaters, Jupiter's moon Europa is covered with a layer of ice, and mountaineers might enjoy Mars where Olympus Mons is almost three times as high as Everest.

Americans seem to think soccer is a game for girls, but the rest of the world calls it football and can be quite obsessive about it. Kronberger 61 in the constellation Cygnus looks like a cosmic soccer ball, though it's another planetary nebula. Unusually - for a soccer ball - it's blue. The light of the nebula comes from the glow of energized oxygen which, unlike the red of hydrogen, is in the blue part of the spectrum.

Family ties
Since a tie is the gift that is to fathers what flowers are to mothers, obviously I have to include one. The Bow Tie Nebula (PGC 3074547) is not a planetary nebula, but a protoplanetary nebula, which is one that's evolving into a planetary nebula. It's rare to find them, as this is a fairly short phase of stellar evolution. The nebula, located about 5000 light years away in Centaurus, has the distinction of being the coldest known natural place in the Universe.

A message in starlight
There was a lovely website that let you write a message – to your father or anyone else – in galaxies. The galaxies came from the Sloane Digital Sky Survey that Galaxy Zoo citizen scientist volunteers helped classify. I used an app to "galactify" this message using galaxies that look rather like letters of the alphabet. Unfortunately, the app is no longer available.

Ethan Siegel, "Could you really hit a golf ball miles and miles on the Moon?"

You Should Also Read:
Mother's Day - an Astronomy Bouquet
What Is a Galaxy
Citizen Science in the Electronic Age

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