On 11 January 1672, the Fellows of the British Royal Society were treated to a demonstration of Isaac Newton’s reflecting telescope, which formed images with mirrors rather than with the lenses that had been used since the time of Galileo. Afterward, the fellows hailed Newton as the inventor of this marvelous new instrument, an attribution that sticks to the present. However, this linear historical account obscures a far more interesting, convoluted story. Newton’s claim was immediately challenged on behalf of two other contenders, James Gregory, and Laurent Cassegrain. More confounding, the earliest known concept of using a curved mirror to focus light predated Newton by more than 1,500 years; the final realisation of a practical reflecting telescope post-dated him by more than a half century.
Continue reading How many great minds does it take to invent a telescope?
Italian astronomer, physicist, engineer, and polymath Galileo Galilei’s (15 February 1564 – 8 January 1642) moon drawings. These were the first realistic images of the Moon, due to Galileo’s training in art and an understanding of chiaroscuro (a technique for shading light and dark) he understood that the shadows he was seeing were actually mountains and craters.
Continue reading Moon Drawings of Galileo Galilei
This… is… amazing!
Astrophotographer Martin Junius recorded this stunning video of the total solar eclipse on March 20, 2015, during the E-Flight AB 1000. In the video, you can see the shadow of the moon moving across the clouds below. The plane was 35,000 feet (10,600 meters) above the Northern Atlantic / Norwegian Sea when the video was recorded.
Continue reading Watch: The shadow of the Moon during a solar eclipse
The Moon is the Earth’s only natural satellite. It is also the fifth-largest natural satellite in the Solar System and the largest among planetary satellites relative to the size of the planet that it orbits. It formed about 4.51 billion years ago from the debris left over after a giant impact between Earth and a Mars-sized body called Theia (this is known as the Giant Impact Hypothesis and is the most widely accepted explanation of the formation of the Moon). This impact happened not long after the Earth has been formed. But, what if that giant impact never happened? What would the Earth without Moon be like?
Continue reading Earth without Moon – what would it be like?
When a meteoroid hits Earth, it’s not because the space rock has “fallen out of” its orbit. It’s because its orbit crosses over Earth’s orbit at the exact right (or wrong) moment.
Continue reading Meteorites do not fall to Earth
As of 2019, only five space probes are leaving the solar system: Pioneer 10, Pioneer 11, Voyager 1, Voyager 2 and New Horizons. The Voyagers already left the solar system and entered the interstellar space (Voyager 1 on August 25, 2012, and Voyager 2 on November 5, 2018. The others also will leave the heliosphere Notes 1 and reach the interstellar space in a few years.
All of these spacecraft are launched by NASA.
Continue reading Five space probes leaving the solar system (for now)
The speed of light is the Universal speed limit – nothing can travel faster than light. In the vacuum (commonly denoted c), its exact value is 299,792,458 meters per second (around 186,000 miles per second). In other words, if you could travel at the speed of light, you could go around the Earth 7.5 times in one second.
Continue reading Speed of Light – See how torturously slow it is
In 1964, Russian astrophysicist Nikolai Kardashev (born April 25, 1932) defined three levels of civilizations, based on the order of magnitude of power available to them:
Continue reading There is most probably no Kardashev Type-III civilization in the Universe. Here’s why
A beautiful Ultima Thule image, taken by the Long Range Reconnaissance Imager (LORRI) aboard NASA’s New Horizons spacecraft in original context against a starry background (i.e., not zoomed in).
Continue reading Ultima Thule image against a starry background
In January 2015, NASA released the largest image ever of the Andromeda galaxy, called the Panchromatic Hubble Andromeda Treasury (PHAT), taken by the Hubble telescope. This composite image involved thousands of observations, hundreds of fields, spanned about a third of the galaxy and resolved over 100 million stars.
Totaling 1.5 billion pixels and requiring 4.3 gigabytes of disk space, this photo provides a detailed glimpse at the sheer scale of our nearest galactic neighbor.
Using this gigantic image, filmmaker Dave Achtemichuk created an unforgettable interactive experience.
Continue reading Watch: 100 Million Stars of the Andromeda Galaxy