Category Archives: Learn

Learn about space and astronomy

What is a blood moon?

Blood moons have historic, religious (Christian and Jewish) and astronomical significance.

Blood Moon - Peter Gaylard
Picture of a blood moon taken by Peter Gaylard using a 15 second exposure of the lunar eclipse from his backyard in Sydney on 28th August 2007 using a Canon 350D camera

From an astronomical perspective, almost any total lunar eclipse could be called a blood moon as the moon does tend to turn a coppery-red colour. Historically, full moons of every month have been given names and the full moon in October was called the “Harvest Moon” or “Blood Moon” or “Sanguine Moon”.

The Biblical aspect of the phrase blood moon comes from end of times prophecy where the moon is supposed to turn blood red. As stated in Joel 2:31

“The sun will be turned to darkness and the moon to blood before the coming of the great and dreadful day of the LORD.”

The recent intrigue surrounding blood moons also comes from the fact that over 2014-2015, we will be seeing four total lunar eclipses in a row without any partial eclipses in between which, will be separated by six full moons. This lunar tetrad, is quite rare with only eight that will occur this century and the ones in 2014-2015 will happen to fall  on the Jewish feasts of Passover and Tabernacles – an even rarer phenomenon, having only occurred seven times before.

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What are falling stars?

Over human history, our ancestors have looked up in the sky wondered about “falling stars” – fiery, bright bolts of light streaking through the sky. What were these strange lights in the sky and where did these “falling stars” come from?

Meteors - NASA
2004 picture of a Geminid meteor shower from Texas

We now know that these are not “stars” at all but are instead small bodies of solid materials travelling through space, called meteors. When meteors pass through the Earth’s atmosphere they generate heat because of the friction between air and the meteor’s surface and end up, burning up in a bright fiery train of light.  Most meteors are destroyed/burned up entirely as they enter our atmosphere with some very small particles surviving down to the Earth’s surface. Large meteors surviving the journey through the atmosphere are very rare.

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What are the planets in our solar system?

Our solar system has eight planets that revolve in orbit around the Sun. These planets, in the order from the Sun are:

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.

Planets
Planets of our solar system

In addition to these eight planets, our solar system also has three “Dwarf Planets” or “Minor Planets”. These smaller planets are Ceres, Pluto and Eris. Pluto was classified as a regular planet until 2006 when it was demoted after a formal definition of what was a planet was established by the International Astronomical Union (IAU).

Mercury, Venus, Earth, and Mars are composed of solid rock and are classified by the IAU as “terrestrials”. The next four planets – Jupiter, Saturn, Uranus and Neptune – are composed of various gases and are classified as “gas giants”.

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What is the Hubble Space Telescope?

Hubble Space Telescope (HST) is a telescope that has been placed in low Earth orbit, about 559 km above the Earth’s surface. Hubble was launched by space shuttle Discovery (STS-31) on April 24, 1990. Unfortunately Hubble was hampered by a flawed optical system until astronauts could make significant repairs in 1993.

Hubble telescope
Hubble telescope with its open aperture door.

The potential benefits of carrying out astronomical observations from space were first suggested in 1923, by the German rocket pioneer Hermann Oberth. NASA worked on several initiatives and conducted proof of concept studies in the 1960s and 1970s that formed the basis of the Hubble Space Telescope. By sitting high above Earth’s atmosphere, Hubble can avoid all the background light and distortions that exist for telescopes on even the most remote areas of Earth. As a result, Hubble has provided astronomers and scientists with some amazing high resolution images of our universe. This has given us invaluable insights into how the universe came about, with some deep views into space and time.

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Why do we have red sunsets?

Red Sunset Canada
Red sunset looking out looking towards the St-Lawrence River – in Rivière-du-Loup, Québec, Canada.

We have all seen beautiful sunsets – sometimes in person and often in pictures that are much like the one above. The sun often sets in  a scintillating reddish-orange aura. Why is the the sun red in colour? Even though it may look red to you when it is setting at your location on Earth, it is also looking bright white to those further to your west where it is not setting.  So we know that the sun itself isn’t really red in colour.

The main reason for the change in its colour is the large distance of the Sun (150,000,000 km) from the Earth. As the sun sets, the distance its light must travel through the Earth’s atmosphere also increases. This atmosphere is composed of many gases, water vapour and numerous particles that affect the sunlight passing through. They can scatter the light, which is made up of all colours, in such a way short-wavelength colours (green, blue, violet) are scattered out and they leave more of the red and yellow frequencies for us to see.

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