Why does the Sun seem red near the horizon? Why does the Moon do the same? We know the Moon isn’t actually changing colour, and the Sun isn’t either. So what is happening to the light? The first thing to note about the image above is that the size of the Moon doesn’t change, showing that the well-known ‘Moon Illusion,’ where the Moon appears larger near the horizon, is just that – an illusion. The second is of course the gradual change in hue as the Moon rises. The reason for the colour shift really has nothing to do with the Moon...
I love false-colour images. They reveal detail that you can’t see in real life, but they also highlight things in an artistic way. For me it’s an excellent marriage of art and science, and as a communicator it helps me get concepts across in an accessible way. So when I saw the APOD image of Saturn from earlier this week, I had to discuss it. Saturn never has looked this way, and it never will. The colours are vivid and unrealistic, but they show the differences in three distinct but close wavelengths of light on the electromagnetic spectrum. All of...
Welcome to a new series of posts that will characterize 1000 amazing facts about the Universe. There is so much out there that we have yet to learn, and every day, astronomers across the globe are using their research to reveal the deepest secrets of the cosmos. This series will look at the strangest, coolest, most exciting facts that we have discovered in hundreds of years of modern science. Fact #4: Most of the stars in the universe are red dwarfs smaller than our Sun. There is a leap of understanding that happens when a child learns that our Sun...
When were the planets discovered? Uranus and Neptune were definitely not found until modern science began, since a telescope was required to see them. The other five planets were not actually discovered per se. Since they are visible to human eyes, they have been observed since prehistoric times, and we see examples of cultures across the ancient world who observed them. The five visible planets are Mercury, Venus, Mars, Jupiter, and Saturn. Starting this weekend, you can see them all across one part of the sky, a visual alignment that hasn’t occurred since 2005. Planets are so-named because of the Greek...
News always reports the records. The biggest, the loudest, the fastest, the first. When it comes to Astronomy, there are so many new worlds to explore and so much new science to learn, we end up breaking records often. Even with Astronomy being the oldest science, the sheer amount of stuff in the universe means there is always something new and surprising to discover. Today’s episode of ‘Biggest, brightest, hottest’ brings us the move massive binary star system ever found, with two huge, hot stars so close together that they are actually touching, merging their atmospheres together. In the Large...
Is this a giant hole in space? I show a picture similar to this as I ask this question to students and audiences that I host in my planetarium. Most people answer that it is a black hole, or dark matter, or dark energy, or something strange like that. But the amazing thing is that it is actually a thick cloud of dust that is opaque, letting no visible light from the distant stars pass through. The funny thing is that the cloud is transparent in infrared light, but in the visible spectrum it highlights something interesting about the universe:...
Why should a galaxy have bluish spiral arms dotted with red patches and dark lanes. Why should it have a central region that is yellow and spherical rather than flat? Why are they flat to begin with? Because Galaxies are so huge, and made from hundreds of Billions of stars that change over the course of their lives, a galaxy shows the entire life cycle of a star in its own structure. Stars are born along spiral arms, where most of the thick dust and gas clouds are concentrated. The dark dust lanes of spiral arms condense to form stars,...
How often does a star explode as a supernova in the Milky Way? With as many as 400 Billion stars, you would expect it to happen often But stars live a very long time, and most massive stars take anywhere from a few hundred million to a few billion years to reach maturity and explode. Putting all this together gives us a surprisingly human estimate. A supernova explodes in the Milky Way, on average, once every 50 years, or about once per human lifetime. We can still see remnants of great explosions that happened long ago, still expanding into the...
When the first stars and galaxies started to form, it was like a spark of a massive chain reaction where the vast amounts of gas and dust that had clumped together were quickly converted into dense, luminous star clusters. This was the beginning of the formation of the heavier elements that would eventually make up all that we see on the planet Earth. But when did this massive tirade of star formation end? When we look at galaxies in the present epoch, most don’t form stars very rapidly at all, and giant elliptical galaxies are all but devoid of gas,...
NASA is sure to start selling trips to these fabulous space destinations! The only problem is that we have no way of getting there, or more importantly, back home. Still the posters give a great homage to the ‘see America’ posters of the 1920s, and they sure make me want to visit. Kepler 186f is a habitable zone planet around a red dwarf star, meaning it could support liquid water. If any plant life forms on this planet, it would photosynthesize differently, potentially giving it a red colour palette. HD 403007g is a planet with 8 times the mass of Earth....
