The TESS mission is following the tradition started by Kepler and finding us planets in places and orbits we never expected. In today’s episode we look at how TESS’s discovery of a Gas Giant in a highly elliptical orbit led to new models looking to imagine how a habitable world might exist in such a system, and what it would see. Beyond dreaming of other worlds skies, we will also talk Monday’s Mercury transit and other celestial events visible this month.


This is the Daily Space for today, Thursday, November 7, 2019. I am your host, Dr Pamela Gay, and I am here to put science in your brain. 

Most Mondays through Fridays, either I or my co-host Annie Wilson, will be here bringing you a quick rundown of all that is new in space and astronomy.


Today’s episode may sound a little bit different. I’m coming to you from Baltimore, Maryland, where I’m attending a meeting on communicating Multi-Messenger Astronomy, and Time Domain Astronomy. My travel, of course, means that our boring news week has turned into, well, a less boring news week. 

Today we had a pair of TESS mission related press releases. The first highlights an image mosaic-ed together from 208 images of the Southern Sky. TESS stands for Transiting Exoplanet Survey Satellite, and this mission is imaging patch after patch of sky, on a rotating basis, looking for planets that pass in front of – or transits their stars. In addition to measuring the slight dimming that accompanies planetary transits, TESS is also sensitive to the light changes that accompany stellar explosions, and that accompany of transitory events, like comets. These 208 images were acquired as TESS imaged 13 different sectors of the Southern sky for a month apiece. All told, TESS has returned 20 terabytes data, containing 29 confirmed exoplanets and more than 1000 planetary candidates. If you would like to study TESS’s mosaic of the Southern sky for yourself, you can find a copy and links to the original NASA site on

In searching for planets, missions like Kepler and TESS have taught us one important fact: solar systems come in more varied forms than anyone had ever previously imagined. As scientists, we’re all working with limited resources, and even theorists had been limited in what they could study by the costs associated with supercomputers and limits on how long code could run. This means that in trying to understand what we expected to find, we often limited our software to only explore parameter spaces where we expected positive results. Our models had systems with only 1 massive Jupiter like world, planets orbited in circles,  and if things varied from that, it was weird, and not many people thought too hard about it. 

That was the past however. Today we know the universe doesn’t care about our preconceived notions about how it should behave, and we have better computers and can explore those situations we hadn’t really thought about before. 

This brings us to our second press release of the day. Earlier this year TESS identified a giant planet orbiting the star HR 5183 with a highly elliptical orbit. As the press release reminds us, “Conventional wisdom says that a giant planet in eccentric orbit is like a wrecking ball for its planetary neighbors, making them unstable, upsetting weather systems, and reducing or eliminating the likelihood of life existing on them.” 

But, as I said, the universe doesn’t care about our Wisdom. Recognizing this, UC Riverside and Caltech astronomers Stephen Kane and Sarah Blunt ran models to see if there were any possible ways to put a habitable planet into a system like HR 5183 that has a Giant Planets that swings comet like through the inner solar system every 75 years. It turns out that while gravity will generally fling away any planets put in the Star’s habitable zone, there are certain combinations that allow a small planet to exist in a stable orbit. This kind of “I wonder if…?” research can excite the imagination, and as if they were trying to encourage science fiction writers to tell their theoretical world’s story, they calculated that when the giant planet passed every 75 years, it would appear 15 times brighter than the brightest apparition of Venus, and would have a clear diameter on the sky. 

So far, no such world has actually been found, and as I said, this possibility was a rare outcome – the majority of possible configurations do lead to the giant world destroying other worlds in it’s system. Still the fact that this kind of a system could exist, means that in the vastness of our universe it probably does exist, and really, someone does need to tell this world’s story. 

It’s always fun to imagine the other worldly skies of planets in remarkable places, like the solar system with a Giant Planet orbiting like a comet. Still, we can’t really complain too much about the planetary views we have from our own planet Earth. This month in particular is a good month to take note of the worlds around us. On Monday. November 11, Earth, the Sun, and diminutive Mercury are going to align so that viewers in the correct places in the world will be able to see Mercury pass directly between the Earth and the Sun and appear as a small black dot on the Sun’s surface. The event is best viewed from South America or the East Coast of Canada and the United States. Viewers to the west will see Mercury already in front of the sun at sunrise, while observers to the East, in Europe and Africa, will lose the end of the event to sunset. While Mercury transits aren’t extraordinary rare, and do occur several times a lifetime, the next transit won’t occur until 2032, so this is worth getting up to see. For East Coast observers, things start around 7:30am.

Always practice safe solar viewing. While you can safely view the sun through eclipse glasses, Mercury is only 1/200 the diameter of the Sun. To see Mercury successfully, you’ll need a safe way to magnify the Sun, and one of the best techniques is to project the sun onto a wall or other large flat surface using binoculars with glass lenses, or a telescope that has been masked to reduce the amount of light entering the instrument. Be careful, the sun is fully capable of melting plastic lenses and damaging mirror coatings. If you have a solar scope, you’ll want a magnification of at least 50. Currently the sun is at solar minimum and sunspots aren’t expected to complicate your view. If you do see Sunspots, it’s worth comparing their color to that of Mercury. Sunspots are actually bright and only appear as spots in contrast to the solar surface around them. Mercury, on the other hand, will be blocking all the Sun’s light. This is the one time that you might be able to tell just how not dark sun spots really are.

If you opt to get up before sunrise, you should also be able to catch Mars, and possibly even Uranus. If you know exactly where to look, Uranus is out there. November 11 might not be the best night to look for it, however, as the moon is pretty much full. Instead, if you want something to do over US thanksgiving, go out to a dark location with a Phone app to help you find things on the sky. Uranus should be high in the sky in the middle of the night, and just visible to the unaided eye if there is no light pollution.


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 made possible through the generous contributions of people like you. If you would like to learn more, please check us out on During the month of November we are running a special fundraiser to support our server costs for 2020. We project costs of $1450 for all of our websites. If you would like to help us reserve our place on the internet, you can donate at Your donations are tax deductible where allowable in the world.

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