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...
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...
Hey hey! It’s a blue moon today! For all those people who have used the phrase ‘Once in a blue moon,’ it finally happened. Turns out that phrase means ‘about once every 2-3 years.’ A blue moon doesn’t mean the moon is changing colour anytime soon, just like a supermoon doesn’t mean the moon actually gains superpowers or gets noticeably bigger. A blue moon is simply the second full moon in a calendar month. The moon orbits the Earth in approximately 29.5 days. This was how months were originally formed. But 12 months x 29.5 days means that we are...
As we push the limits of our technology, we naturally will find the biggest, the brightest, the smallest, the most extreme, and of course the most distant objects in the universe. We are at the time in history where we are beginning to see the edges of our universe in unprecedented detail. Eventually will will stop finding the biggest, brightest, and most distant, after which point our technology will serve to improve our precision and allow us to peer within these unique objects. Astronomers have used this incredible technology to discover the most distant galaxy in the universe, forming only...
