It was hard enough to find ‘Oumuamua, the first object on an interstellar trajectory discovered within our own Solar System. The emergence of new resources like the Large Synoptic Survey Telescope (LSST) should help us develop a preliminary catalog of such interlopers, thought to be not uncommon if we can identify them. But tracking down objects that wandered from one star to another and found their way into residence in our system is another matter entirely. In April we looked at a study of an unusual set of Centaurs, asteroids whose orbit perpendicular to the orbital plane of the planets and other asteroids raises questions about their origin. A letter to Monthly Notices of the Royal Astronomical Society had appeared, written by Fathi Namouni (Observatoire de la Côte d’Azur, France) and Maria Helena Moreira Morais (Universidade Estadual Paulista, Brazil). The scientists identified what seems to be a population of asteroids that were probably drawn into the Sun’s gravitational pull...

In addition to being a rather well-known character on television, SPOCK also stands for something else, a software model its creators label Stability of Planetary Orbital Configurations Klassifier. SPOCK is handy computer code indeed, determining the long-term stability of planetary configurations at a pace some 100,000 times faster than any previous method. Thus machine learning continues to set a fast pace in assisting our research into exoplanets. At the heart of the process is the need to figure out how planetary systems are organized. After all, after the initial carnage of early impacts, migration and possible ejection from a stellar system, a planet generally settles into an orbital configuration that will keep it stable for billions of years. SPOCK is all about quickly screening out those configurations that might lead to collisions, which means working out the motions of multiple interacting planets over vast timeframes. To say this is computationally demanding is to greatly...

I hadn’t planned to write about the recent work out of the University of Exeter on Beta Pictoris, but yesterday’s article on KELT-9b dealt with planetary alignment, given that the planet shows marked spin-orbit misalignment. At Beta Pictoris, an international team of researchers led by Exeter’s Stefan Kraus has carried out measurements of the spin-orbit alignment of Beta Pictoris b, a gas giant orbiting a young star in an orbit about as distant as Saturn from the Sun. Here we have the first spin-orbit alignment measurement of a directly imaged planetary system. How such alignments occur is clearly relevant to planet formation theories. There’s a bit of astronomy history here, for spin-orbit issues became significant for both Immanuel Kant (1724-1804) and Pierre-Simon Laplace (1749-1827), who looked at spin-orbit alignment in our own Solar System. It was apparent to both that the planets known to them orbited the Sun not only in alignment with each other but in alignment with the...

Perhaps the hottest planet ever discovered spotlights yet another way to interpret light curves produced by transiting worlds. KELT-9b comes out of data gathered by the KELT transit survey, the acronym standing for Kilodegree Extremely Little Telescope. KELT consists of two robotic telescopes, one at Winer Observatory in southeastern Arizona, the other at the South African Astronomical Observatory in Sutherland, South Africa. The planet orbits an A-class star in Cygnus about 670 light years away and turned up in the KELT data in 2017. We’ve learned a lot more about KELT-9b thanks to the TESS mission, allowing us to understand just how unusual this planet is. 2.9 times as massive as Jupiter, the world orbits its star in 36 hours, receiving 44,000 times the energy from its host that Earth receives from the Sun. Reaching 4,300 degrees Celsius, this is a tidally locked planet whose dayside is hotter than the surfaces of some stars. Its orbital path takes it almost directly above both the...

In exoplanet research, 'deserts' are regions where things are not found. Thus the Neptunian Desert, which is a zone close to a star where planets of Neptune size only rarely appear. Deserts like this (there is also a Brown Dwarf Desert that we've examined in earlier posts) raise questions because we don't know why they occur. What is it we don't understand about planet formation that accounts for the lack of Neptune-mass planets in 2-4 day orbits? Exceptions tweak our thinking, and do have NGTS-4b, a world 20 percent smaller than Neptune and 20 times as massive as Earth in a 1.3-day orbit around a K-dwarf (see Into the Neptunian Desert for more on this one, which is now joined by an even more puzzling object). For today we learn of the discovery of a world of roughly Neptune's mass with an orbital period of a scant 18 hours, and researchers reporting the discovery in Nature suggest that we are actually looking at a 'failed' gas giant, an exposed planetary core. We can thank TESS...

Ramses Ramirez, whose work on what he calls the Complex Life Habitable Zone was the subject of a recent Alex Tolley essay (see Are Classic Habitable Zones Too Wide for Complex Life?), joins us today with a look back at Rare Earth on the occasion of the book's 20th anniversary. Written by Peter Ward and Donald Brownlee, Rare Earth examined a wide range of factors that argued against the ubiquity of complex life in the cosmos. I remember well when it came out, as I was in the midst of writing my Centauri Dreams book for Copernicus, Ward and Brownlee's publisher, and my editor (the brilliant Paul Farrell) and I had to wrestle with the question of whether Rare Earth rendered the search for intelligent life elsewhere irrelevant. Fortunately, we plunged ahead anyway. As Dr. Ramirez shows this morning, many of the factors put forward by Ward and Brownlee can be re-examined with new data as work on exoplanets continues. Ramses is a research scientist at the Earth-Life Science Institute...