My initial take, based also on useful inputs from & interactions with @HarrisonD@jrl and @alter_hugo below (thanks to all!)
Facts & data
Here are the numbers discovered per year since 2013, obtained from the full catalog filtered for p_habitable > 0 (for the habitable number) and per year (for the total number):
Year
Number (habitable)
Number (total)
2013
7
127
2014
8
875
2015
8
156
2016
11
1517
2017
9
153
2018
1
324
2019
3
203
2020
10
233
2021
1
526**
2022
5
365
2023
5
304
2024*
N/A
12***
* provisional
** big discrepancy with Wikipedia, which reports only 258; the rest of the values are roughly similar (but not exactly equal) to the Wikipedia-reported ones
*** obtained from the NASA Exoplanet Archive interactive tool, with 'Discovery Year' set to 2024 and 'Solution Type' set to 'Published Confirmed'; last updated on (or after) Feb 10. Wikipedia reports 38
A few things are directly apparent from the table:
As others have already pointed out, the base rate for the question here is ~73% (8 out of 11 years), and the condition for 5 or more new discoveries has been met (albeit only marginally) for the last 2 years (2022 & 2023)
Contrary to what a rough intuition/expectation may dictate (and many people have argued below), the rate of discovery is not increasing for either number (habitable worlds and total)
There does not even seem to be any meaningful correlation between the total number of exoplanets and the number of habitable ones discovered per year
If we accept the value of 12 total exoplanets discovered so far (Feb 10) for 2024, @NukePirate's observation below that the year is off to a very slow start seems accurate
Discussion & analysis
The relatively high numbers of yearly discoveries between 2013 and 2017 can be largely attributed to the Kepler space telescope, launched in 2009 and retired on Oct 2018, which had the detection of exoplanets as its primary mission. Although new exoplanets have been discovered from Kepler data as recently as 2023, its last contribution to the habitable worlds catalog were 2 exoplanets in 2020 (Kepler-1701 b and Kepler-1649 c).
Several people below have expressed confidence that the James Webb space telescope (JWST), launched on Dec 2021 and in full operation since mid-2022, will lead to the discovery of more (habitable) worlds, hence nudging the question here toward Yes; but truth is, as @HarrisonD has already reported below (and I have independently confirmed), JWST's contribution so far has been just one single exoplanet in 2023, and it was not a habitable one. Although studying exoplanets is included in the JWST mission objectives, it is not very clear to me that detecting new ones is (although this preprint of Jan 2024 seems to be just about that).
After Kepler was retired, the new workhorse on exoplanet detection seems to be the Transiting Exoplanet Survey Satellite (TESS). Since its launch in April 2018, TESS has discovered 420 confirmed exoplanets, including at least four (4) potentially habitable ones; notice that the 'Detection Facility" column of the data includes entries such as "Multiple Observatories" and "Multiple Facilities", so although only 4 worlds are listed by TESS, it could be implicitly included in these other entries, too.
Not all instruments hunting exoplanets are space-based. The Calar Alto observatory in Spain is running the CARMENES survey, which has contributed so far at least 4 worlds in the habitable list of interest (plus possible more under "Multiple", as described above for TESS); it has been reported that the program would run at least until the end of 2023, but its current status is unknown to me (inputs welcome). Other earth-based observatories involved in the search for exoplanets include the Subaru telescope in Hawaii (1 habitable world in 2022) and the ESO's La Silla observatory in Chile, which has been contributing steadily to the list of habitable worlds since 2013 (13 worlds in total so far).
Delays in the lists update (and a concern about resolution)
My understanding is that an exoplanet is considered confirmed (and thus included in the relevant lists) after the relevant publication has been accepted in a peer-reviewed journal; very often, when such a thing happens, the (accepted) manuscript is posted at arxiv as a preprint, and the date of acceptance (and not of actual publication, which can take a few months more) counts as the discovery date.
As of writing (Feb 29), the resolution source was last updated on Feb 1, i.e. a month ago. If we take the resolution criteria literally, it would seem that the question will be closed and resolved on Dec 31; but assuming monthly updates of our resolution source, this means that worlds possibly discovered in December will most probably be not included in the list yet on Dec 31. So, I will very kindly suggest to the admin team (@FP@henrytolchard@dante) to issue a clarification, assuring that, although the question will be closed on Dec 31, it will not be resolved until we are sure that the lists have been actually updated up to Dec 31.
Updates between updates
Our lists of interest seem to be updated on a monthly basis; in-between, there seem to be a couple of sources that can offer possible hints of new discoveries:
The NASA Exoplanet Archive News offers weekly updates on new exoplanet discoveries, but it does not include information about their potential habitability. They even offer a newsletter subscription.
The NASA Exoplanets Exploration page also offers "alerts" when new exoplanets are discovered. Their latest alert of Jan 31 was about a super-earth in the habitable zone, TOI-715 b, but the planet is already included in our resolution lists for 2023.
Conclusion and forecast
With the situation as exposed above, I don't find any reason to deviate upward from the base rate of 73%; on the contrary, there seem to be some reasons to deviate downward (seemingly slow start of 2024, possibility that we are exhausting the low-hanging fruits), so I'm gonna start with 70% for the time being. I am currently assuming that the clarification I have suggested above will be granted, otherwise I will have to move lower.
5 new discoveries in the next 11 months translate to a rate of ~0.45/month; in other words, we would need at least 1 discovery per quarter (and then some) to reach Yes here. Again, this assumes that the suggested clarification will be granted, otherwise we are effectively talking for 5 discoveries in 10 months, for a required rate of 0.5/month (and a discovery every 2 months) instead.
Files
Why might you be wrong?
It would be great if someone could cross-check the data I have provided above!
This is a very good analysis of the problem, IMHO.
"The Astrophysical Journal Letters" seems to publish 18 times per year, so every 2-3 weeks. That means we're probably not waiting for quarterly updates to data - it's relatively current at all times.
One thing I just thought of is that the definition of habitability periodically undergoes revision based on new science; not clear to me whether people go back and revise P_HAB numbers for all data points when that happens.
Yeah, just roughly kicking the tires on the parameters of the problem.
One more thought: people book time on space telescopes years in advance. If there happens to be a block of cosmologists using a big chunk of resources in Jan/Feb, that probably reduces planet-finding time in that period. That may reverse itself during other periods of time. Might explain part of the lumpiness in the data, beyond the randomness of actual distribution.
As I say above, it would seem that the date of discovery is determined by the date of acceptance for publication to a peer-reviewed journal; there is just too long and complicated and case-specific and largely stochastic a process between observations and final manuscript acceptance to be of any use for us here, IMO. Plus, not all sensors work that way (i.e. with booking observation time) - I think TESS is just scanning predetermined sky sections, and then people just go through the data (as they still do with data from the now retired Kepler)...
Why do you think you're right?
My initial take, based also on useful inputs from & interactions with @HarrisonD @jrl and @alter_hugo below (thanks to all!)
Facts & data
Here are the numbers discovered per year since 2013, obtained from the full catalog filtered for p_habitable > 0 (for the habitable number) and per year (for the total number):
* provisional
** big discrepancy with Wikipedia, which reports only 258; the rest of the values are roughly similar (but not exactly equal) to the Wikipedia-reported ones
*** obtained from the NASA Exoplanet Archive interactive tool, with 'Discovery Year' set to 2024 and 'Solution Type' set to 'Published Confirmed'; last updated on (or after) Feb 10. Wikipedia reports 38
A few things are directly apparent from the table:
Discussion & analysis
The relatively high numbers of yearly discoveries between 2013 and 2017 can be largely attributed to the Kepler space telescope, launched in 2009 and retired on Oct 2018, which had the detection of exoplanets as its primary mission. Although new exoplanets have been discovered from Kepler data as recently as 2023, its last contribution to the habitable worlds catalog were 2 exoplanets in 2020 (Kepler-1701 b and Kepler-1649 c).
Several people below have expressed confidence that the James Webb space telescope (JWST), launched on Dec 2021 and in full operation since mid-2022, will lead to the discovery of more (habitable) worlds, hence nudging the question here toward Yes; but truth is, as @HarrisonD has already reported below (and I have independently confirmed), JWST's contribution so far has been just one single exoplanet in 2023, and it was not a habitable one. Although studying exoplanets is included in the JWST mission objectives, it is not very clear to me that detecting new ones is (although this preprint of Jan 2024 seems to be just about that).
After Kepler was retired, the new workhorse on exoplanet detection seems to be the Transiting Exoplanet Survey Satellite (TESS). Since its launch in April 2018, TESS has discovered 420 confirmed exoplanets, including at least four (4) potentially habitable ones; notice that the 'Detection Facility" column of the data includes entries such as "Multiple Observatories" and "Multiple Facilities", so although only 4 worlds are listed by TESS, it could be implicitly included in these other entries, too.
Not all instruments hunting exoplanets are space-based. The Calar Alto observatory in Spain is running the CARMENES survey, which has contributed so far at least 4 worlds in the habitable list of interest (plus possible more under "Multiple", as described above for TESS); it has been reported that the program would run at least until the end of 2023, but its current status is unknown to me (inputs welcome). Other earth-based observatories involved in the search for exoplanets include the Subaru telescope in Hawaii (1 habitable world in 2022) and the ESO's La Silla observatory in Chile, which has been contributing steadily to the list of habitable worlds since 2013 (13 worlds in total so far).
Delays in the lists update (and a concern about resolution)
My understanding is that an exoplanet is considered confirmed (and thus included in the relevant lists) after the relevant publication has been accepted in a peer-reviewed journal; very often, when such a thing happens, the (accepted) manuscript is posted at arxiv as a preprint, and the date of acceptance (and not of actual publication, which can take a few months more) counts as the discovery date.
As of writing (Feb 29), the resolution source was last updated on Feb 1, i.e. a month ago. If we take the resolution criteria literally, it would seem that the question will be closed and resolved on Dec 31; but assuming monthly updates of our resolution source, this means that worlds possibly discovered in December will most probably be not included in the list yet on Dec 31. So, I will very kindly suggest to the admin team (@FP @henrytolchard @dante) to issue a clarification, assuring that, although the question will be closed on Dec 31, it will not be resolved until we are sure that the lists have been actually updated up to Dec 31.
Updates between updates
Our lists of interest seem to be updated on a monthly basis; in-between, there seem to be a couple of sources that can offer possible hints of new discoveries:
The NASA Exoplanet Archive News offers weekly updates on new exoplanet discoveries, but it does not include information about their potential habitability. They even offer a newsletter subscription.
The NASA Exoplanets Exploration page also offers "alerts" when new exoplanets are discovered. Their latest alert of Jan 31 was about a super-earth in the habitable zone, TOI-715 b, but the planet is already included in our resolution lists for 2023.
Conclusion and forecast
With the situation as exposed above, I don't find any reason to deviate upward from the base rate of 73%; on the contrary, there seem to be some reasons to deviate downward (seemingly slow start of 2024, possibility that we are exhausting the low-hanging fruits), so I'm gonna start with 70% for the time being. I am currently assuming that the clarification I have suggested above will be granted, otherwise I will have to move lower.
5 new discoveries in the next 11 months translate to a rate of ~0.45/month; in other words, we would need at least 1 discovery per quarter (and then some) to reach Yes here. Again, this assumes that the suggested clarification will be granted, otherwise we are effectively talking for 5 discoveries in 10 months, for a required rate of 0.5/month (and a discovery every 2 months) instead.
Why might you be wrong?
It would be great if someone could cross-check the data I have provided above!
This is a very good analysis of the problem, IMHO.
"The Astrophysical Journal Letters" seems to publish 18 times per year, so every 2-3 weeks. That means we're probably not waiting for quarterly updates to data - it's relatively current at all times.
One thing I just thought of is that the definition of habitability periodically undergoes revision based on new science; not clear to me whether people go back and revise P_HAB numbers for all data points when that happens.
Sure, but the AJP is hardly the only venue for such publications, right?
And yes, the risk of revisions to the definition is real, and something we'll have to live with.
Yeah, just roughly kicking the tires on the parameters of the problem.
One more thought: people book time on space telescopes years in advance. If there happens to be a block of cosmologists using a big chunk of resources in Jan/Feb, that probably reduces planet-finding time in that period. That may reverse itself during other periods of time. Might explain part of the lumpiness in the data, beyond the randomness of actual distribution.