Carl Sagan and space exploration: The effects of popularising science

Photograph of Carl Sagan with a model of the Viking lander.

First published on 6th April 2016. Last updated on 5th June 2017 by Dr Helen Klus

In the 1960s, science journalism in the United States was sparse and mostly performed by journalists with little or no scientific background. Science was perceived as minimising the need for pseudoscience, but it didn't fill the spiritual void this left in people. »

Cycles of destruction: The link between comet and asteroid impacts and mass extinctions on Earth

Photograph of the Ouarkziz Impact Crater in Algeria.

First published on 28th January 2016. Last updated on 5th June 2017 by Dr Helen Klus

Over 180 impact craters have been identified on Earth, and most of these were discovered in the first half of the 20th century. Impacts have been associated with mass extinction events since the 1980s, with strong evidence coming from the Chicxulub Crater, which was linked to the extinction of most of the dinosaurs about 65 million years ago. »

Devouring stars: The science of supermassive black holes

Artist's impression of a flare emanating from a supermassive black hole.

First published on 27th December 2015. Last updated on 5th June 2017 by Dr Helen Klus

In November 2015, a team of scientists led by Sjoert van Velzen of Johns Hopkins University and Gemma Anderson of ICRAR (the International Centre for Radio Astronomy Research) in Perth discovered what happens when a supermassive black hole devours a star. »

Planetary formation patterns and the probability of alien civilisations existing in the universe

Painting showing astronauts working on a space colony that contains land and oceans.

First published on 24th November 2015. Last updated on 5th June 2017 by Dr Helen Klus

Our understanding of planets has increased dramatically in the last decade, particularly since the launch of NASA's Kepler satellite in 2009. This has resulted in the detection of thousands of extra-solar planets, and led to a better understanding of how planets form. »

Water in space: Evidence of flowing liquid water on Mars

Mountain on Mars that contains flowing water.

First published on 29th September 2015. Last updated on 5th June 2017 by Dr Helen Klus

In September 2015, NASA announced that they've found evidence of liquid water currently flowing on Mars. This began with the discovery of dark streaks on the sides of several craters. These are up to a few hundred meters long, and appear seasonally. »

Would we be able to detect an alien spacecraft before it reaches Earth?

Photograph of Earth from space.

First published on 26th August 2015. Last updated on 5th June 2017 by Dr Helen Klus

It seems likely that alien life has evolved somewhere in the Galaxy, given that there may be millions of habitable planets, and many of these may have existed for billions of years. If just one species in the whole of the Galaxy were able to explore using self-replicating spacecraft, then they might be able to place probes across the Galaxy within a million years or so. »

A Brief History of Pluto: Dwarf planets, the Kuiper Belt, and New Horizons

Mountains on Pluto

First published on 29th July 2015. Last updated on 5th June 2017 by Dr Helen Klus

Mercury, Venus, Mars, Jupiter, and Saturn are all visible with the naked eye, and can be distinguished from stars because they move around the sky in a different way. The orbits of the planets were determined in the 1600s, and confirmed with telescopes, which had just started to be used in astronomy. »

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The Star Garden is a science news and science education website run by Dr Helen Klus.

How we came to know the cosmos covers the history of physics focusing on space and time, light and matter, and the mind. It explains the simple discoveries we made in prehistoric times, and how we built on them, little by little, until the conclusions of modern theories seem inevitable. This is shown in a timeline of the universe.

The Star Garden covers the basics for KS3, KS4, and KS5 science revision including SATs, GCSE science, and A-level physics.