Why are new planets still news? And why is the sky red?

25 years after the discovery of exoplanets, and more than 4000 planets later we’re still getting press releases on new planets. In this episode we argue planet discoveries are now science as usual. We then take a look at how the ash from fires and the Tael Volcano are changing the color of the sunset, and for some the color of our days.

Sometimes we as scientists forget to think of Earth when we think of planets. At NASA, they divide things up into Helioscience, Earth Science, Planetary Science, and Astrophysics, as if to say our Sun isn’t a Star and our Earth isn’t a planet. Historically, these divisions are based on how differently we could study our Earth compared with other worlds, and on how much more information we can get about our Sun compared to other stars.

Over the decades, how we do science has changed, and how we understand our universe has evolved, and these 4 categories make it hard for us to know where to put the study of exoplanets, how to file papers comparing Earth and Mars terrains using rovers and people in the field, and in general, we need a new classification system.

But change is slow. 

• “Cold Neptune” And Two Temperate Super-Earths Found Orbiting Nearby Stars (Carnegie)

2020 is the 25th anniversary of the discovery of planets orbiting stars other than our Sun. In the past few years we’ve started finding planets with masses not too different to Earth’s mass, and it seems that every few weeks there is a new announcement about new world in some star’s habitable zone. This week is one of those weeks. In a new paper in the Astrophysical Journal Supplement Series, a team of researchers led by Canegie’s Fabo Feng and Paul Butler announce the discovery of two super Earths, with passes 7.5 & 7.9 times the mass of Earth. These two planets orbit different red dwarf stars, and may be positioned such that they can have liquid water on their surface. These planets, along with 3 other confirmed worlds and 8 candidate worlds, expand our catalogue of more than 4000 planets outside our solar system. At this point, I’m not sure the discovery of a new world around yet another red dwarf is still news or astronomy as usual. I am seeing the bias of so many of us journalists being old enough to have grown up without exoplanets, so we’re still like “Oh cool – PLANET”. But at some point, we need to probably just admit, stars generally have planets, planets regularly exist in habitable zones, and as long as we keep looking for planets, we’re going to keep finding planets. At this point, I think that unless something truly novel is discovered, we’re going to stop calling the new planets news. If it is a particularly slow news day, we may do a periodic round up of newly found worlds.

• Rayleigh Scattering Sunsets (Physics Central)
• Q&A: How Climate Change, Other Factors Stoke Australia Fires (VOA News)

If I sound like a curmudgeon, it may be because it’s a stormy Friday with unrelenting cold and cloud and ice pellets falling from the sky. Weather and light both affect mood. I can’t really complain, however. There are places in Australia and New Zealand where the sky is red with ash. For those of you farther away and with clear skies, you may have noticed that the Sunsets recently have been truly spectacular, with deeper reds then we’re used to. 

What you’re seeing is an effect called Rayleigh Scattering. As light passes through any material, whether it be a gas nebula, our atmosphere, or just a cloudy fish tank, the light passing through the material has two options – it can head straight through, or it can get scattered through interactions with the material. While every photon of light has the potential to pass through or be scattered, the probabilities vary with color. Red light is much more likely to pass through than blue light. Astronomically, this causes us to see nebulae lit from behind as red, and nebula lit from the side – reflection nebulae – as blue. In our day to day lives, this is why a cloudy fishtank lit from the top will appear slightly blue, and this is why the light through smoke is red. There have been some tweets out there basically saying the sky is red with reflected fire. While that may sometimes be the case, the same way clouds at night appear orange from sodium lights in cities, the reality is that sunlight passing through smoke clouds turns the day red by scattering out the blue light to the sides.

The same is true of ash from volcanoes, and right now, the combined particles from the Australian fires and Tael Volcano in the Philippines are spreading through out the world’s atmosphere and causing amazing sunsets, a more golden hue in general, and for many difficulty in breathing. 

Some folks have asked if these particles can help drop the Earth’s temperature, and combat climate change. While short term effects from volcanoes have been seen, these are temporary effects that don’t change the problem that we have too many greenhouse gasses in our atmosphere and being released into our atmosphere. Any temporary changes will be reversed as the particles settle out of the atmosphere, and we will be left with a world that has fewer forests. 

Today, these are literally darker times, as we get less light. Tomorrow, or more like several months from now, things we continue to settle into a new normal that will include new and more massive fires, and the normal punctuation of volcanic eruptions. 

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And that rounds out our show for today.

Thank you all for listening. The Daily Space is produced by Susie Murph, and is a product of the Planetary Science Institute, a 501(c)3 non profit dedicated to exploring our Solar System and beyond. We are here thanks to the generous contributions of people like you. Want to become a supporter of the show? Check us out at Patreon.com/cosmoquestx 

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