Category Archives: Articles

Citizen scientists spot meteorite strike during lunar eclipse

This week’s total lunar eclipse featured a dramatic bonus: shortly after the start of totality, a space rock hit the moon and vaporised in a flash of light. My latest piece for Physics World tells the story…

Can you spot the lunar flash…?
Here is a link to the moment of impact on our broadcast. It’s on the left edge of the moon, just below the 10 o’clock position, at 04:41:43 UTC.

Astronomy beyond sight

Our favourite astronomy professor Richard Gelderman (Western Kentucky University) and I have produced two stories for EarthSky about astronomers who are exploring the universe through hearing and touch.

In Listening to the patterns of the universe, Richard talks to Wanda Díaz Merced (International Astronomical Union) about using ‘sonification’ to find signals hidden in large data sets; in Astronomy beyond sight, Amelia Ortiz-Gil (University of Valencia) tells me how she uses tactile models to bring people into contact with the constellations, moon and planets.

The complicated relationship between science and sci-fi

How important is the science in science fiction? I talked to three big thinkers – physicist and philosopher David Deutsch, film-maker Olga Osorio, and scientist turned novelist Gianfranco D’Anna – for a piece in Physics World.

What can lunar eclipses do for science?

As part of the build-up to the July 27th/28th total lunar eclipse, Sky & Telescope have published an interview I did with Noah Petro, Project Scientist for NASA’s Lunar Reconnaissance Orbiter mission.

What is the saros cycle and how does it foretell eclipses?

My latest article for Sky & Telescope begins 2,500 years ago in ancient Babylon, and ends with next week’s total lunar eclipse.

Sky and Telescope, 24 January 2018

Coming soon to a sky near you: a teachable moment

There are 100 days to go until the next eclipse… On January 31st 2018 a total lunar eclipse will produce a red full moon for people in parts of Asia, Australia and the Pacific, and North America.

Total lunar eclipse (Juan Carlos Casado)Image: Juan Carlos Casado

Why does the moon turn red? The earth – a rocky planet about 13,000 km across – moves between the sun and the moon. This blocks the sun’s rays from reaching the moon directly.

But the earth has an atmosphere – a layer of air about 100 km thick. The atmosphere bends some of the sun’s rays around the earth (this is called refraction; it’s why a straw looks bent when you see it in a glass of water). The atmosphere also filters out the blue colour from the sun’s rays (this is called scattering; it’s why the sky looks blue).

So the sun’s rays that eventually reach the moon – after having travelled around the earth, through the atmosphere – are red. This is what gives the moon its awe-inspiring change of colour.

If you miss the red moon in January – because of weather, geography or some other reason – you might get another chance six months later. On July 27th/28th 2018 there will be a total lunar eclipse across Africa, Europe, Asia and Australia. And six months after that – on January 20th/21st 2019 – there will be another total lunar eclipse across North America, South America, Europe and parts of Africa.

Thank you to the brilliant Science Learning Hub for the pages on refraction and scattering.


Mystery of the moon’s tilted orbit

I’m extremely grateful to the brilliant planetary scientist Kaveh Pahlevan, who shared some wonderful thoughts in this interview for EarthSky. “When a crime happens, investigative police quickly arrive on the scene and try to preserve the evidence. In the case of the moon’s origin, there was a violent event, but there were no witnesses, and we are arriving on the scene five billion years late!”

How a solar eclipse made Einstein famous

Images: Wikimedia / CC-PD-Mark

We all know the genius on the left. But who is the genius on the right…?

My latest article for Sky & Telescope magazine asks: “Why do some great scientists become household names, whereas others do not? Why, these days, does everyone in the world know who Einstein is (and what he looked like)? On the other hand, when we do a Google search for ‘Maxwell’, why does the scientist who unified electricity, magnetism and light appear below a musician with the same name? The answers to these questions will lead us to a solar eclipse that took place across South America and Africa 98 years ago.”

“A need to know and increased motivation to learn”

“For cranking motivation levels up to eleven, nothing says ‘teachable moment’ like a solar eclipse…” Sky & Telescope magazine has an article about our science outreach project in Angola :)

Africa gets ready for another sun and moon show


Mail & Guardian Africa has published a piece about next weekend’s African eclipse, and our Angolan “Global Communication and Science” project.


Africa gets ready for another sun and moon show
Graham Jones | Mail & Guardian Africa | 17 February 2017

Six months after Africa played host to a spectacular eclipse of the sun, it will happen all over again. Shortly before sunset on February 26th, an annular solar eclipse – where the sun forms a ‘ring of fire’ around the moon – will be visible in parts of Angola, Zambia and the DRC. Across the rest of continent, most places will experience a partial eclipse.

Solar eclipses occur when the moon passes between the earth and the sun. But there’s a catch: the moon’s orbit around the earth is slightly tilted, which means it is rare for the earth, moon and sun to line up exactly. Although the most recent African eclipse occurred on September 1st last year, when an annular eclipse swept across the continent from Gabon to Madagascar, the next annular eclipse in Africa won’t be until 2020; for the next total eclipse in Africa (where the moon covers the sun completely) we’ll have to wait until 2027.

In the very late afternoon of February 26th, a partial solar eclipse will be visible across western, central and southern Africa. In Lagos, 24% of the sun’s disk will be covered by the moon, starting at 4:46 pm, with the maximum eclipse at 5:41 pm (all the times given in this article are local times). In Kinshasa it will be a 69% partial eclipse (4:31 pm start, 5:36 pm maximum); in Johannesburg it will be 52% (5:14 pm start, 6:13 pm maximum).

The ring of fire will be visible along a narrow ‘path of annularity’ running from the small town of Bentiaba on the coast of Angola, through the northern tip of Zambia’s North-Western Province, to the city of Likasi in the south-east of the DRC. The dramatic effect is caused by the moon being too far away from the earth to cover the sun completely, so the dark moon becomes surrounded by a thin ring of the sun’s bright disk. (The world annular means ‘ring-shaped’.)

The largest city on the path of annularity is Huambo, in Angola’s central highlands. Here the ring of fire will begin at 5:28 pm, and last up to half a minute in the southern part of the city. (The city lies right on the northern limit of the path of annularity, so the ring of fire is not visible in the northernmost areas of the city.)

Huambo is the focal point of a series of educational events being planned for the eclipse. The Angolan Ministry of Higher Education, and the Provincial Government of Huambo, have given their backing to a Global Communication and Science project taking place at the Instituto Superior de Ciências de Educação do Huambo (ISCED). The planned activities include a public workshop and seminar at ISCED, classroom activities for schools, and a live broadcast of the eclipse in partnership with the astronomy network Slooh.

The events in Huambo are being sponsored by, the world’s largest time-zone related website, and a leading supplier of eclipse information. “We are very excited about this collaboration,” commented Steffen Thorsen, the chief executive officer of the website’s parent company. “People everywhere will be able to follow the annular eclipse in Angola as it happens, and we hope to inspire people of all ages about the wonders of eclipses.”

The project is also being backed by Angola NCR, the leader in Angola’s IT sector, who are sponsoring solar eclipse glasses being given to members of the local community. “The February 26th eclipse creates an exciting and important educational opportunity,” said Eduardo Lobato, NCR’s operations manager. “Over the past year we’ve been focussed on strengthening our relationship with universities and students, in an effort to promote the values of innovation and technology, and support developments in Angola’s education sector.”

In the map at the top of this article, the path of annularity is shown as a thin red line. The other shadings indicate the areas where a partial eclipse is visible: dark orange – more than 90%; medium orange – up to 90%; light orange – up to 40%. No eclipse is visible in the white areas. You can obtain full details for your town or city here.

NEVER look at the sun with the naked eye. Even if the sun is 99% covered by the moon, the remaining sunlight is extremely bright and can cause permanent damage to the eye. Click here for information on how to protect your while eyes watching the sun.