Venus is close-by and similar in size to Earth, but until recently, we couldn’t tell much about it. Dr. Rakesh Mogul, Professor of Chemistry and Biochemistry, at Cal Poly Pomona took another look at old Venus data to potentially change what we know about our sister planet. Dean chats with Dr. Mogul to unravel the mystery.
Send us your thoughts at lookingup@wvxu.org or post them on social media using #lookinguppodcast
Dean Regas's Guide: Where to Find the Naked-Eye Planets
Saturn: Evening Sky, About halfway up in the southern sky. Looks yellow in color.
Jupiter: Evening Sky, Rising in the east after 9pm. Looks incredibly bright.
Mercury: Morning Sky, Very low in the southeast just before sunrise in December only. Looks like a little orange star.
Venus: Not visible for a few months, it's going behind the Sun this month. Venus will shift into the morning sky in late February 2026.
Mars: Not visible for a few months, it's also going behind the Sun (but further behind). Mars will pop out into the evening sky in April 2026.
Episode Transcript:
Looking Up is transcribed using a combination of AI speech recognition and human editors. It may contain errors. Please check the corresponding audio before quoting in print. This transcript may include additional material from the conversation, not featured in the audio.
Dean Regas: What’s that bright star in the sky? Is it a star? Is it a plane? A UFO? It’s definitely suspicious looking.
Maybe you’ve gotten up early before sunrise and seen this mysterious light in the sky. Or you’ve been driving home after work and, hanging there in the twilight, there’s a beacon that almost seems to follow you. What is that thing, anyway?
It’s the planet Venus!
And although Venus can be our closest planet we couldn’t tell much about it until very recently. So, mysterious!
From the studios of Cincinnati Public Radio, I’m your host, Dean Regas, and this is Looking Up! The show that takes you deep into the cosmos or just to the telescope in your backyard to learn more about what makes this amazing universe of ours so great.
My guest today is Rakesh Mogul, professor of chemistry and biochemistry at Cal Poly Pomona, who took another look at old Venus data to potentially change what we know about our sister planet.
So, I’ve often heard of Venus referred to as our sister planet, but let me yell you, it is one twisted sister. First of all Venus has this atmosphere that just blocks everything. Blocks our attempts to see through it, and also hold this unimaginable heat.
The surface has air pressure that has about 92 times that of Earth so it would pretty much squish you flat. And then when it rains, it rains sulfuric acid. I always thought it would be the greatest job to be a weatherman on Venus…
[Dean as Venus Weatherman]: This is Dean Regas with your planetwide forecast. Today will be like every other day here on Venus: 900 degrees and cloudy with a slight chance of acid rain.
Dean Regas: I’m getting ahead of myself. Didn’t I say we don’t know anything about Venus? How did we find all this stuff?
We can’t see the surface from Earth. So the only way we know this is from missions: Landers and atmospheric craft. The only problem is they kind of didn’t work real great because well, they got crushed in the atmosphere and melted in the heat.
So, it really wasn’t until the the Magellan spacecraft got out there, it was the first to map the surface and use radar to penetrate the clouds.
So, I kind of thought all of the missions that attempted to land on Venus were like complete failures. But my guest today says, oh no. We just need to take another look at the data.
Rakesh Mogul: Hi, my name is Rakesh Mogul. I’m a professor at Cal Poly Pomona. and I do quite a bit of work on Venus astrobiology and Venus planetary science.
Dean Regas: Well, Rakesh, thanks so much for joining me today.
Rakesh Mogul: Glad to be here. Thank you for the invitation.
Dean Regas: Now we’re going to be talking a lot about Venus, and I was hoping maybe you could help describe what the conditions are like on this planet.
Rakesh Mogul: Venus is very different from Earth. It’s crazy hot at the surface. Very barren. Just a lot of rocks. Then there’s the atmosphere. The atmosphere is dominated by carbon dioxide with a little bit of nitrogen and a number of really, really trace atmospheric gases. Then, as you get into the clouds, there’s a very thick cloud layer and there’s quite a bit of sulfuric acid. There is something in the clouds that likes to absorb ultraviolet light, and this has been a bit of a mystery for several decades now. What is the identity of these ultraviolet absorbers?
Dean Regas: Well, and you know, Venus does have this veil of mystery around it. What’s our exploration history like from all the missions we sent, both from the U.S. and Soviet Union?
Rakesh Mogul: It’s a quite rich history. We’ve sent several probes toward Venus. Several probes failed on the Soviet side. They sent a few that were just impactors that went through the atmosphere, collected some data, then impacted the ground real hard. They actually sent several ones that landed somewhat softly and were able to take measurements on the surface for a little while. Then they also sent what are called descent probes, which more slowly descended the clouds and measured a bunch of information as the descent progressed.
And then we did the same thing, we being Americans. We sent a couple spacecraft: one that orbited Venus for quite a long time, and the other that separated kind of like a transformer, if you will. It was called the multiprobe, and it went to Venus, then separated into about four or five different pieces, and they all went into the atmosphere and landed in different places.
The main one was part of the Venus large probe, which had a lot of different instruments on it and gave us a bunch of information that we still use today.
There was a European orbiter called Venus Express, and the Japanese also had some spacecraft that orbited Venus that are still in orbit but are no longer collecting data.
So, there is a rich history, but all that history basically ended in the ’80s.
Dean Regas: So, you had this idea you’re like, what if we look at this old data? And you’re like, well, maybe we can get something out of that. I’ve always been told we hardly got any information from those Venus things because they all crashed and burned and melted. But what could you find that nobody else saw before?
Rakesh Mogul: Well, we were interested in the composition of the atmosphere. So, I was having a discussion with a colleague of mine, Sanjay Limaye, who’s basically an encyclopedia for Venus stuff. And he, in real time, was like, hey, well, they had gas chromatographs and mass spectrometers that were on the probe. And in real time on a phone call, he’s sending me emails with the references.
So, I take a look at that, and after a couple of weeks, I realized that there were trends in the data that weren’t published anywhere. And that then set off kind of a cascade of events. We realized from reading the papers that they actually measured the mass spectra, which is basically measuring how many different molecules are in the atmosphere and what they approximately weigh. And so, they measured this at several different altitudes, but they only published one of these spectra, which means all the other ones were buried somewhere.
So, we went through this whole process of trying to find out where the spectra were. And then it was found and it was on microfilm and they had to go through some special processes to convert it from microfilm to PDF So, then we were off and running, and there wasn’t really a lot of information about how they collected the information and how they really built the instrument.
So, that set off another wave of detective work on our end like sleuthing, if you will, where me and another colleague, Michael Way, went to the University of Texas at Dallas and searched around a couple of different buildings and offices looking for the old notebooks, going back to like 1969 all the way to about 1979. And we actually got a lot of really old archive information. And then Michael Way and I also went to NASA Ames, where they have a nice archive history office, and worked with them. They were really helpful in helping us find old project mission reports really old ones where they described what the instruments were, what they did, how they built them, and some of their controls and calibrations.
So, putting all that together, we were able to really have a much better understanding of how the data was collected and what it really meant. And then I think this is where it separates us from perhaps the previous investigators: I have a pretty solid background in chemistry, organic chemistry, and using mass spectrometry for this and that. And pretty early on we realized that there were a lot of trends in the data that were just never analyzed and definitely not published.
Dean Regas: And so, what did you find that was unhighlighted before?
Rakesh Mogul: The first thing we found was evidence of a phosphorus-based species in the clouds, where this thing, if it’s a phosphorus species, should be a gas. The dominoes started to fall. What else is buried in this data? The big one was a water signal. There’s a lot of water, and especially in the deep lower atmosphere.
The previous investigators assigned the first big water peak to sulfuric acid. When sulfuric acid decomposes by thermal means or by heat, it does release water, so they assigned that one correctly.
Then there was this huge water signal way down around 10 kilometers, and they thought that this was contamination from Earth and wrote the whole thing off.
So, I looked at it and saw that the SO,₂ profile had the same shape as the water profile, which should not be the case. If they’re the same shape, they probably have the same root cause.
So, that then led me to believe, OK, maybe this water isn’t a contamination. Maybe it’s actually from these trapped aerosols and it’s in a different form of water than one might think not like a glass of water where all the water’s freely floating around and can just come off into a vapor phase. But maybe it’s bound up by something.
So, then that really led us to understanding that the aerosols are probably not as pure as people think they are. They actually contain quite a bit of iron So, probably the form of iron sulfide. And then that iron sulfate probably has lots of water molecules bound to it.
So, this really opens the door to rethinking the composition of the aerosols of Venus’ clouds.
Dean Regas: Well, I have to back up. You might have seen my eyebrows raise when you said the word “species,” and you know where my mind went right away. I was like, wait a second. Is Rakesh saying there are aliens in the atmosphere of Venus or…
Rakesh Mogul: Chemical species. Chemical, chemical species.
Dean Regas: Well wait. What’s a chemical species?
Rakesh Mogul: A chemical species would be any chemical. We call them chemical species in the chemical literature. But I am definitely not talking about life forms. I am talking about individual chemicals.
Dean Regas: Oh shoot. Boy, I thought we had a breaking news alert here with us. Ooh boy, we are going to put you on your creative spot here. You delved into the mystery of Venus’s atmosphere. If you wanted to give it a nice title, the case of the… what?
Rakesh Mogul: Yeah, that is a good one. Let me think about that. There are a couple of different ways I could see this.
Dean Regas: The case of the missing water, or the case of…mis-identified… the forgotten water. I do not know.
Rakesh Mogul: I love that. I love that. That is perfect. Actually that is one hundred percent perfect. The case of the forgotten water at Venus.
Dean Regas: Because that is the way you described it. It was there, but they did not make much of it, or they wrote it off because they thought it was contamination.
Rakesh Mogul: Just to dive into that a little bit some of the Venera probes, actually all of the Venera probes and the Vega measurements, and the Pioneer Venus ones every instrument that went into the clouds and directly sampled, physically acquired a sample and analyzed it every one of those measurements got high water. All of them.
However, if you measured it from a distance, where you did not directly sample but indirectly measured it spectroscopically using light, all of those give low water. It is totally cut and dry. Indirect measurements give low; direct measurements give high. So, it has been written off as instrument contamination or faulty design.
So, it is a case of the forgotten water in Venus’s atmosphere.
Dean Regas: Are you influenced by the mystery genre? Were you taking this on as a detective? Did you put on your Sherlock Holmes hat and say, we are going to get to the bottom of this?
Rakesh Mogul: Absolutely. Sherlock Holmes, Hercule Poirot, Agatha Christie it is all there. We are trying to solve what is going on here using whatever technology we have. And my colleagues are all into that. We are all laser focused. We are uncovering documents that are 50 years old and trying to understand what these folks did back then, and why they wrote off such groundbreaking results that have been sitting there collecting dust for 50 years.
But it is one thing to have it. How do we present this to the outside world and have them believe us, when most people think this data is garbage? So, we had to do this systematically. Start with the really basic, boring stuff the internal calibrators. Analyze those. One step at a time.
It was definitely detective work that had to be patient, really going through this and not giving up, and honing in on what I think is my chemistry background knowing there are chemical trends here, but needing patience to elucidate what the trends are.
Dean Regas: Well, Rakesh, thanks So, much for joining me today to talk about all these things with Venus. And congratulations on your investigative work. It sounds like it was a lot of fun.
Rakesh Mogul: Thank you. It was a lot of fun. Thanks for having me.
Dean Regas: One of the most common questions I get is: How can you tell a planet from a star in the sky?
As a rule, planets twinkle less than stars. That is because they are reflecting light from the sun, and the planets are large enough in our sky that the light comes to us as a wider beam. Starlight comes as pinpoints from much farther away, which scatters more easily in our atmosphere. Thus, planets do not twinkle as much as stars.
With the naked eye, you can see five planets. No telescope or binoculars needed. I am talking Mercury, Venus, Mars, Jupiter, and Saturn. They wander across the background stars, but not very quickly. Once you find them, you can get to know them.
Venus has been blazing in the predawn sky this fall, visible just before sunrise. But it is slowly moving behind the sun from our perspective and will mostly be invisible until it pops out in the evening sky in February 2026.
So, I am giving you some homework. See if you can find where the other four naked-eye planets are tonight and when to look for them. Wait, am I actually giving you homework? Yeah. But do not worry we will list them on our website too. But you should totally find them on your own.
Looking Up with Dean Regas is a production of Cincinnati Public Radio. Kevin Reynolds and I created the podcast in 2017. Ella Rowen and Carlos Lopez Cornu produce and edit our show and have suggested that if I want audio from on location on Venus, I should, quote, “get it yourself.” Yeah, they are definitely producers.
Jenell Walton is our vice president of content, and Ronny Salerno is our digital platforms manager. Our theme song is “Possible Light” by Ziv Moran. Our social media coordinator is Hannah McFarland, and our cover art is by Nicole Tiffany.
I am Dean Regas. Keep looking up!
