Some ‘water worlds’ like Jupiter’s moon Europa could potentially be habitable for life. NASA/JPL-Caltech/SETI InstituteDaniel Apai, University of Arizona The search for life beyond Earth is a key driver of modern astronomy and planetary science. The U.S. is building multiple major telescopes and planetary probes to advance this search. However, the signs of life – called biosignatures – that scientists may find will likely be difficult to interpret. Figuring out where exactly to look also remains challenging. I am an astrophysicist and astrobiologist with over 20 years of experience studying extrasolar planets – which are planets beyond our solar system. My colleagues and I have developed a new approach that will identify the most interesting planets or moons to search for life and help interpret potential biosignatures. We do this by modeling how different organisms may fare in different environments, informed by studies of limits of life on Earth.
New telescopes to search for life
Astronomers are developing plans and technology for increasingly powerful space telescopes. For instance, NASA is working on its proposed Habitable Worlds Observatory, which would take ultrasharp images that directly show the planets orbiting nearby stars. My colleagues and I are developing another concept, the Nautilus space telescope constellation, which is designed to study hundreds of potentially Earthlike planets as they pass in front of their host stars.Future telescopes, like the proposed Nautilus, could help search the skies for habitable planets.Katie Yung, Daniel Apai /University of Arizona and AllThingsSpace /SketchFab, CC BY-ND These and other future telescopes aim to provide more sensitive studies of more alien worlds. Their development prompts two important questions: “Where to look?” and “Are the environments where we think we see signs of life actually habitable?” The strongly disputed claims of potential signs of life in the exoplanet K2-18b, announced in April 2025, and previous similar claims in Venus, show how difficult it is to conclusively identify the presence of life from remote-sensing data.
When is an alien world habitable?
Oxford Languages defines “habitable” as “suitable or good enough to live in.” But how do scientists know what is “good enough to live in” for extraterrestrial organisms? Could alien microbes frolic in lakes of boiling acid or frigid liquid methane, or float in water droplets in Venus’ upper atmosphere? To keep it simple, NASA’s mantra has been “follow the water.” This makes sense – water is essential for all Earth life we know of. A planet with liquid water would also have a temperate environment. It wouldn’t be so cold that it slows down chemical reactions, nor would it be so hot that it destroys the complex molecules necessary for life. However, with astronomers’ rapidly growing capabilities for characterizing alien worlds, astrobiologists need an approach that is more quantitative and nuanced than the water or no-water classification.
A community effort
As part of the NASA-funded Alien Earths project that I lead, astrobiologist Rory Barnes and I worked on this problem with a group of experts – astrobiologists, planetary scientists, exoplanet experts, ecologists, biologists and chemists – drawn from the largest network of exoplanet and astrobiology researchers, NASA’s Nexus for Exoplanet System Science, or NExSS. Over a hundred colleagues provided us with ideas, and two questions came up often: First, how do we know what life needs, if we do not understand the full range of extraterrestrial life? Scientists know a lot about life on Earth, but most astrobiologists agree that more exotic types of life – perhaps based on different combinations of chemical elements and solvents – are possible. How do we determine what conditions those other types of life may require? Second, the approach has to work with incomplete data. Potential sites for life beyond Earth – “extrasolar habitats” – are very difficult to study directly, and often impossible to visit and sample. For example, the Martian subsurface remains mostly out of our reach. Places like Jupiter’s moon Europa’s and Saturn’s Moon Enceladus’ subsurface oceans and all extrasolar planets remain practically unreachable. Scientists study them indirectly, often only using remote observations. These measurements can’t tell you as much as actual samples would.Mars’ hot, dusty surface is hostile for life. But scientists haven’t been able to study whether some organisms could lurk beneath.NASA/JPL-Caltech/Malin Space Science Systems To make matters worse, measurements often have uncertainties. For example, we may be only 88% confident that water vapor is present in an exoplanet’s atmosphere. Our framework has to be able to work with small amounts of data and handle uncertainties. And, we need to accept that the answers will often not be black or white.
A new approach to habitability
The new approach, called the quantitative habitability framework, has two distinguishing features: First, we moved away from trying to answer the vague “habitable to life” question and narrowed it to a more specific and practically answerable question: Would the conditions in the habitat – as we know them – allow a specific (known or yet unknown) species or ecosystem to survive? Even on Earth, organisms require different conditions to survive – there are no camels in Antarctica. By talking about specific organisms, we made the question easier to answer. Second, the quantitative habitability framework does not insist on black-or-white answers. It compares computer models to calculate a probabilistic answer. Instead of assuming that liquid water is a key limiting factor, we compare our understanding of the conditions an organism requires (the “organism model”) with our understanding of the conditions present in the environment (the “habitat model”). Both have uncertainties. Our understanding of each can be incomplete. Yet, we can handle the uncertainties mathematically. By comparing the two models, we can determine the probability that an organism and a habitat are compatible. As a simplistic example, our habitat model for Antarctica may state that temperatures are often below freezing. And our organism model for a camel may state that it does not survive long in cold temperatures. Unsurprisingly, we would correctly predict a near-zero probability that Antarctica is a good habitat for camels.A hydrothermal vent deep in the Atlantic Ocean. These vents discharge incredibly hot plumes of water, but some host hearty microorganisms.P. Rona / OAR/National Undersea Research Program (NURP); NOAA We had a blast working on this project. To study the limits of life, we collected literature data on extreme organisms, from insects that live in the Himalayas at high altitudes and low temperatures to microorganisms that flourish in hydrothermal vents on the ocean floor and feed on chemical energy. We explored, via our models, whether they may survive in the Martian subsurface or in Europa’s oceans. We also investigated if marine bacteria that produce oxygen in Earth’s oceans could potentially survive on known extrasolar planets. Although comprehensive and detailed, this approach makes important simplifications. For example, it does not yet model how life may shape the planet, nor does it account for the full array of nutrients organisms may need. These simplifications are by design. In most of the environments we currently study, we know too little about the conditions to meaningfully attempt such models – except for some solar system bodies, such as Saturn’s Enceladus. The quantitative habitability framework allows my team to answer questions like whether astrobiologists might be interested in a subsurface location on Mars, given the available data, or whether astronomers should turn their telescopes to planet A or planet B while searching for life. Our framework is available as an open-source computer model, which astrobiologists can now readily use and further develop to help with current and future projects. If scientists do detect a potential signature of life, this approach can help assess if the environment where it is detected can actually support the type of life that leads to the signature detected. Our next steps will be to build a database of terrestrial organisms that live in extreme environments and represent the limits of life. To this data, we can also add models for hypothetical alien life. By integrating those into the quantitative habitability framework, we will be able to work out scenarios, interpret new data coming from other worlds and guide the search for signatures of life beyond Earth – in our solar system and beyond. Daniel Apai, Associate Dean for Research and Professor of Astronomy and Planetary Sciences, University of Arizona This article is republished from The Conversation under a Creative Commons license. Read the original article.
Why can’t it always be summer? It’s all about the Earth’s tilt
Earth’s axial tilt causes the seasons. As Earth orbits the Sun, different hemispheres tilt toward or away, creating summer and winter depending on location.
Why can’t it always be summer? – Amanda, age 5, Chile
With its long days just itching to be spent by water doing nothing, summer really can be an enchanting season. As Jenny Han wrote in the young adult novel “The Summer I Turned Pretty”: “Everything good, everything magical happens between the months of June and August.”
But all good things must come to an end, and summer cannot last forever. There’s both a simple reason and a more complicated one. The simple reason is that it can’t always be summer because the Earth is tilted. The more complicated answer requires some geometry.
I’m a professor of geography and the environment who has studied seasonal changes on the landscape. Here’s what seasons have to do with our planet’s position as it moves through the solar system.
This animation shows why the Earth has seasons.
Closeness to the Sun doesn’t explain seasons
First, you need to know that the Earth is a sphere – technically, an oblatespheroid. That means Earth has a round shape a little wider than it is tall.
Every year, Earth travels in its orbit to make one revolution around the Sun. The Earth’s orbit is an ellipse, which is more like an oval than a circle. So there are times when Earth is closer to the Sun and times when it’s farther away.
A lot of people assume this distance is why we have seasons. But these people would be wrong. In the United States, the Earth is 3 million miles closer to the Sun during winter than in the summer.Our distance from the Sun is not why we have seasons. NASA
Spinning like a top
Now picture an imaginary line across Earth, right in the middle, at 0° latitude. This line is called the equator. If you drew it on a globe, the equator would pass through countries including Brazil, Kenya, Indonesia and Ecuador.
Everything north of the equator, including the United States, is considered the Northern Hemisphere, and everything south of the equator is the Southern Hemisphere.
Now think of the Earth’s axis as another imaginary line that runs vertically through the middle of the Earth, going from the North Pole to the South Pole.
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As it orbits, or revolves, around the Sun, the Earth also rotates. That means it spins on its axis, like a top. The Earth takes one full year to revolve around the Sun and takes 24 hours, or one day, to do one full rotation on its axis.
This axis is why we have day and night; during the day, we’re facing the Sun, and at night, we’re facing away.
But the Earth’s axis does not go directly up and down. Instead, its axis is always tilted at 23.5 degrees in the exact same direction, toward the North Star.
The Earth’s axis is tilted due to a giant object – perhaps an ancient planet – smashing into it billions of years ago. And it’s this tilt that causes seasons.Because of the tilt of the Earth, we are able to experience the seasons. Stephanie Spera
It’s all about the tilt
So that means in June, the Northern Hemisphere is tilted toward the Sun. That tilt means more sunlight, more solar energy, longer days – all the things that make summer, well, summer.
At the same time, the Southern Hemisphere is tilted away from the Sun. So countries such as Australia, Chile and Argentina are experiencing winter then.
To say it another way: As the Earth moves around the Sun throughout the year, the parts of the Earth getting the most sunlight are always changing.
Fast-forward to December, and Earth is on the exact opposite side of its orbit as where it was in June. It’s the Southern Hemisphere’s turn to be tilted toward the Sun, which means its summer happens in December, January and February.
If Earth were not tilted at all, there would be no seasons. If it were tilted more than it is, there would be even more extreme seasons and drastic swings in temperature. Summers would be hotter and winters would be colder.The Earth’s axis is always tilted at 23.5 degrees. Stephanie Spera
Defining summer
Talk to a meteorologist, climate scientist or author Jenny Han, and they’ll tell you that for those of us in the Northern Hemisphere, summer is June, July and August, the warmest months of the year.
But there’s another way to define summer. Talk to astronomers, and they’ll tell you the first day of summer is the summer solstice – the day of the year with the longest amount of daylight and shortest amount of darkness.
The summer solstice occurs every year sometime between June 20 and June 22. And every day after, until the winter solstice in December, the Northern Hemisphere receives a little less daylight.
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Summer officially ends on the autumnal equinox, the fall day when everywhere on Earth has an equal amount of daylight and night. The autumnal equinox happens every year on either September 22 or 23.
But whether you view summer like Jenny Han or like an astronomer, one thing is certain: Either way, summer must come to an end. But the season and the magic it brings with it will be back before you know it.
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And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.
The science section of our news blog STM Daily News provides readers with captivating and up-to-date information on the latest scientific discoveries, breakthroughs, and innovations across various fields. We offer engaging and accessible content, ensuring that readers with different levels of scientific knowledge can stay informed. Whether it’s exploring advancements in medicine, astronomy, technology, or environmental sciences, our science section strives to shed light on the intriguing world of scientific exploration and its profound impact on our daily lives. From thought-provoking articles to informative interviews with experts in the field, STM Daily News Science offers a harmonious blend of factual reporting, analysis, and exploration, making it a go-to source for science enthusiasts and curious minds alike. https://stmdailynews.com/category/science/
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Arizona scholarships 2026: Arizona scholarships are open through ACF: one application for 160+ awards, plus ARAC’s $1,500 Ashby-Herring scholarships due April 6, 2026.
Scholarship season moves fast, and for a lot of Arizona families, the hardest part isn’t writing the essay or gathering transcripts—it’s simply finding the right opportunities in time.
The Archer Ragsdale Arizona Chapter (ARAC), Tuskegee Airmen, Inc. is encouraging students and the community to take advantage of scholarship resources through the Arizona Community Foundation (ACF), including an easy online application that can match applicants with 160+ scholarships—plus virtual workshops where students can get help directly from ACF’s scholarship team.
Whether you’re a high school senior, a current college student, or an adult re-entry student, ACF’s scholarship portal is designed to meet people where they are.
The Big Picture: One Application, 160+ Scholarships
According to the flyer, ACF awarded $6.3 million in scholarships last year, with over 160 scholarships available through a single, easy application.
What to watch for: Even if a student is only targeting one scholarship, completing the ACF application can surface additional matches they didn’t know existed.
ARAC (Tuskegee Airmen, Inc.) awards two or more scholarships to deserving Arizona students who are college-bound. The flyer highlights the Ashby-Herring scholarships, named in honor of late founding ARAC members who were original Tuskegee Airmen.
Free Virtual Workshops (Zoom): Get Help With Your Application
If you’ve ever watched a student stall out halfway through an application, these workshops are a smart fix: they’re designed so applicants can work on their scholarship application with support from ACF’s scholarship team.
Workshop dates (Zoom):
February 12, 2026 — 4:00 to 5:00 p.m.
March 5, 2026 — 4:00 to 5:00 p.m.
March 26 — 4:00 to 5:00 p.m. (date listed on flyer; confirm year when registering)
What to watch for: Register for the dates you can attend and come prepared with what you already have (basic info, activities list, questions). One hour of guided progress can save days of procrastination.
Why This Matters (and Why Sharing Helps)
The Tuskegee Airmen legacy is rooted in excellence, discipline, and breaking barriers—and scholarships tied to that legacy are meant to elevate futures for the next generation.
If you’re a parent, teacher, coach, mentor, or neighbor, consider this your nudge: forward the link, post it in a group chat, or share it with a student who might qualify. Deadlines hit quickly, and the easiest scholarship to win is often the one you actually apply for.
College isn’t just classes and credits — it’s learning how to manage your time, money, health, and relationships while you build a future that actually fits. In our College Life coverage, STM Daily News shares practical, real-world guides for students and families: campus living tips, study and productivity habits, career prep, budgeting basics, mental wellness check-ins, and smart ways to make the most of college in Arizona and beyond.
Expect quick reads, useful takeaways, and “what to do next” advice — whether you’re a first-year student, a transfer, or heading back to school.
Traveling to Mexico this spring? Here’s what to know about current advisories
Traveling to Mexico this spring? Visitors should be aware of state-specific travel advisories, as safety concerns in one region do not affect major resort areas like Cancun and Los Cabos, currently rated Level 2, which encourages increased caution. Monitoring official updates is essential for informed travel decisions amidst evolving conditions.
Traveling to Mexico this spring? Here’s what to know about current advisories
(Tiffany Miller for ALG Vacations) For some travelers counting down to spring break, recent headlines about violence in parts of Mexico have sparked a new question: Should I cancel my trip? Travel advisors say they are seeing a surge in calls and emails from clients trying to determine whether developments in one region affect major resort areas elsewhere.
The questions follow several days of unrest in parts of Mexico after security operations targeting organized crime leaders prompted temporary flight disruptions and shelter-in-place guidance for U.S. government personnel in areas including Puerto Vallarta and Guadalajara. In this article, ALG Vacations explains what current travel advisories mean for spring break travelers heading to Mexico.
The U.S. State Department evaluates Mexico state by state, not as a single destination, and advisory levels vary by region. Many major beach destinations, including Cancun, Riviera Maya, Tulum and Los Cabos, are currently under a Level 2 advisory, which encourages travelers to exercise increased caution. It does not discourage travel.
Part of the confusion stems from geography. Puerto Vallarta, on the Pacific coast, is roughly 1,300 miles from Cancun and the Riviera Maya on the Caribbean side, about the distance between New York and Miami. Because advisories are assigned state by state, developments in one region do not automatically alter another.
In recent days, that uncertainty has translated into additional inquiries about whether specific resort areas are experiencing disruptions. U.S. Embassy security alerts issued this week indicate that temporary shelter-in-place guidance affecting Puerto Vallarta was lifted and that flight operations resumed. The advisory level for the Mexican state of Quintana Roo remains unchanged.
Some clients are asking about alternatives, advisors say, but many are continuing with their plans after reviewing official updates. Travel patterns often shift in response to breaking headlines, they add, before stabilizing as clearer information becomes available.
The State Department assigns travel advisories on a four-tier scale ranging from Level 1, exercise normal precautions, to Level 4, do not travel. While Level 2 encourages increased awareness, Level 3 and Level 4 carry stronger language discouraging or restricting travel.
Advisories are reviewed regularly and can be updated as conditions evolve. The State Department’s Mexico advisory page breaks down conditions by state, reflecting the country’s federal structure rather than issuing a single national designation. Travelers can also enroll in the State Department’s Smart Traveler Enrollment Program, which provides real-time security updates and allows U.S. officials to contact citizens in an emergency.
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Embassy notices state that airports, hotels and tourism services in Quintana Roo are operating normally. Security conditions across Mexico vary widely by state, with some regions carrying higher advisories and others designated Level 1. Most destinations popular with U.S. travelers are currently classified as Level 2.
As spring break approaches, advisors say informed decision-making depends on reviewing the advisories assigned to a specific destination and monitoring official updates, rather than reacting to national headlines alone. Travel decisions ultimately depend on individual comfort levels, they add, but advisory levels are assigned regionally and should be evaluated accordingly.
Welcome to the Consumer Corner section of STM Daily News, your ultimate destination for savvy shopping and informed decision-making! Dive into a treasure trove of insights and reviews covering everything from the hottest toys that spark joy in your little ones to the latest electronic gadgets that simplify your life. Explore our comprehensive guides on stylish home furnishings, discover smart tips for buying a home or enhancing your living space with creative improvement ideas, and get the lowdown on the best cars through our detailed auto reviews. Whether you’re making a major purchase or simply seeking inspiration, the Consumer Corner is here to empower you every step of the way—unlock the keys to becoming a smarter consumer today!
