Photons in a bucket

MOON SHOT: Angus Bodle's cellphone picture of the moon.

A cellphone blu-tacked to a telescope got young astrophotographer Angus Bodle up close to the moon for a picture. Astrophotography might not be art as we know it but it is out there.

It captures the beauty of the skies, says president of the Gisborne Astronomical Society, and of the Royal Astronomical Society of New Zealand, John Drummond.

Instead of the white and grey disc we are familiar with from countless pictures of our nearest neighbour in space, Angus’s moon is a dirty orange, scarified with blast lines that radiate from a navel, as it were, where an asteroid up to two kilometres in diameter struck it.

TYCHO

Named after 16th century, Danish astronomer Tycho Brahe, the bright ray crater is a relative spring chicken at around 108 million years old. Tycho Brahe was the last of the major naked-eye astronomers. His research is said to have been five times more precise than the other astronomers’ measurements. Among the aberrations in his life was the loss of the bridge of his nose in a duel. For the rest of his life he wore a brass prosthetic nose.

The long spokes that radiate from the crater stretch as far as 1500 kilometres. Sections of these rays can be seen even when Tycho is illuminated only by earthlight. The rays were formed by material that was “splattified” when the asteroid hit the planet, says Drummond.

As the dark areas in Angus’s picture shows the moon is also awash with lava seas known as mare. Not the stuff bad dreams are made of, but oceans. Oceans created long ago by volcanoes on the moon.

“Areas of the moon got smacked with asteroids and rocks,” says Drummond.

“Lava beneath the surface seeped up and flooded the plains and formed those dark areas called mare.”

A DRIZZLE OF PHOTONS

To ensure photons that have taken centuries in Earth time to get here are captured, long exposures are often needed.

“It’s not like taking a picture at one one-hundreth of a second,” says Drummond.

“Things in the sky are so faint we need to keep the camera open for a long time.”

He likens the process to catching rain in a bucket. Put the pail under a downpour and within a short few minutes it fills up.

For the astrophotographer, photons are more like a fine drizzle.

“In the sky the objects are so faint it takes hours for the bucket to fill. It takes patience. We can spend hours collecting faint photons.”

Former Gisborne astronomer John Burt’s picture of stars wheeling around the bronze statue of Nicholas Young was made possible with digital technology.

“In the old days of film we would have to leave the shutter open for six hours or more to get a photograph like that,” says Drummond.

“John shot about 300 two-minute exposures then he stacked them together. With digital photography you can do that. General users of film couldn’t do that.”

COMET LOVEJOY

Burt’s 2014 Christmas Day picture of Comet Lovejoy was shot from Te Wherowhero Lagoon. The use of a wide-angled lens meant Burt could capture more of the reflection of the comet’s long tail on the water in his picture.

The comet was named after Australian astronomer Terry Lovejoy who is known among astrophotographers for his discovery of a way to modify filters in digital cameras that cut off infrared light. The filters also cut off some of the red light that many deep space objects emit. Lovejoy’s procedures enabled amateur astronomers to improve their deep space photography.

The comet lies alongside the faint, but distinctive line of the Milky Way. Light pollution is a growing issue for astrophotographers and astronomers, but with the city’s light spill behind him, Burt was able to get a clear picture.

Light pollution is a growing issue for astrophotographers and astronomers but with the city’s light spill behind him, Burt was able to get a clear picture.

ETA CARINAE

After a one-and-a-half hour exposure on a DSLR camera mounted on a telescope Drummond got his picture of deep space stellar system Eta Carinae.

Made up of hydrogen and helium the giant gas cloud is a stellar system that contains at least two stars with a combined luminosity greater than five million times that of the Sun.

Eta Carinae ejected the giant, psychedelic cloud during an outburst in the 19th century. This material forms a twin-lobed dust-filled cloud known as the Homunculus Nebula. It is now about one light year long.

“Light from Eta Carinae takes 7500 years to reach us,” says Drummond. “It left in early Babylonian times.

“Invisible stars embedded in hydrogen and helium are flooding the area with ultra-violet light. It makes the cloud glow with a pinkish colour.”

Most of the universe is gas, he says. Hydrogen and helium were the first atoms created after the Big Bang and are the first two elements in the Periodic Table.

Dust forms a faint nebulosity around the brightest stars in Drummond’s picture of the star cluster Pleiades/ Matariki. The cluster is dominated by hot-blue, luminous stars.

“They’re blue stars so they are quite young,” says Drummond.

By “quite young” he means they formed within the past 100 million years. Another former member of the Gisborne Astronomical Society, Otto Gruebl, left the East Coast to shoot the 2012 transit of Venus from Uluru in Australia’s Northern Territory.

“Otto loves to photograph the sun,” says Drummond. “His pictures of the surface of the sun are quite detailed.”

TRANSIT OF VENUS

The orange-yellow colour at the centre of Gruebl’s transit of Venus picture graduates into orange-infused red at the circumference. Because the image is two-dimensional it is easy to forget the magnetic storms that spew up flames seen bursting out of the circumference actually cover the surface of the star.

The ‘zits’ on the surface are sunspots while the small black dot sailing in front of the sun gave European scientists 248 years ago the opportunity to calculate an astronomical unit with which the solar system could be measured

In a pan-European collaboration various expeditions were made so observations of the transit could be made from various locations. Lieutenant James Cook’s scientists observed the rare astronomical event from Tahiti in 1769.

“The astronomical unit helped put things in perspective,” says Drummond.

Gruebl used the same technology — a Panasonic GF5 MFT camera fitted with the lens on the ocular of a Coronado Solar Max II 60 telescope — to shoot from Page Glen Canyon in the US the 2012 annular eclipse.

The difference between a total eclipse and an annular eclipse is the moon is further away from the earth during an annular eclipse.

Gruebl’s red-rimmed circle recalls the black sun motif pioneer psychologist Carl Jung described as the “little spark without which the darkness would not be darkness”.

Which doesn’t sound a million miles away from astrophotography.