The Science of Summer

Why does ice cream look different when it melts in your car and gets refrozen?
If you have ever made homemade ice cream, you may have noticed that it takes a lot of work. My family’s ice cream maker looked a lot like this one which was electric but needed a little more monitoring than the ones we have today.

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The key to some good ice cream is keeping it at the perfect temperature and keeping it moving. Commercial creameries have special machines that continually stirs the ice cream while it is being frozen. These machines cool the ice cream much more quickly than my home machine ever could, which is why their ice cream is much creamier. It prevents larger ice crystals from freezing in the ice cream.

When ice cream melts in the Houston heat on your way home from the grocery store, you may notice that it’s not quite the same consistency any more. If you put the ice cream back into the freezer, it will refreeze, but over a longer period of time than the original ice cream. In addition when you re-freeze the ice cream, you aren’t churning the mixture. This allows larger crystals to form which affects its appearance and its creamy consistency. It is not recommended to refreeze ice cream that has been left out for a longer period of time. Ice cream is made out of dairy, so it can grow bacteria or spoil if left out for too long!

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How does sunscreen actually work?
First, we have to talk about what happens to cause your skin to burn. When you are out in the sun, your skin is exposed to sunlight which is made from ultraviolet (UV) radiation. Ultraviolet radiation can be subdivided into three categories based on wavelength. UV-A radiation has the longest wavelength. It is not absorbed by our atmosphere’s ozone layer and it is the type of UV that is responsible for long term skin damage. UV-B radiation has a shorter wavelength than UV-A. Some of the UV-B radiation is absorbed by the ozone layer and the remaining UV-B radiation that reaches the earth’s surface is responsible for sunburns. The last type of UV radiation is UV-C radiation. It has the shortest wavelength and it is completely absorbed by our atmosphere. On the Earth’s surface, we are not affected by UV-C radiation, but it could be an issue for astronauts if they didn’t have those protective suits. Sunscreen protects our skin from the two most common forms of UV radiation on the earth’s surface – UV-A and UV-B.

Essentially, sunscreen forms a thin, invisible protective layer on the surface of our skin. It uses organic and inorganic active ingredients to form that protective layer. The organic ingredients such as octyl methoxycinnamate and oxybenzone absorb UV rays. When the rays are absorbed, the energy is harmlessly dissipated in the form of heat. Some of the organic materials in sunscreen will slowly break down over time, which is why we need to reapply sunscreen regularly. The inorganic active ingredients like zinc oxide or titanium dioxide reflect the UV radiation essentially preventing the UV radiation from hitting the skin. Early versions of sunscreen were opaque and white, which reflected the UV radiation well. However, it wasn’t the most appealing look for the beach. With newer technology, they’ve made these inorganic materials much smaller and nearly invisible.

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How can I cool down a warm beverage quickly?
It’s the middle of summer, and when you walk outside it feels like you have walked through a curtain of heat and humidity. Nothing sounds better in a Houston summer than a nice, cold drink. But we’ve all forgotten to move something from the pantry to the fridge, and ended up with a warm drink instead. Even when you move that drink to the fridge, it can take over 45 minutes to reach the cool temperature you’d prefer. Here are a few ways to cool down your beverage quickly, and the science on how it works.

Option 1: The Wet Paper Towel Method.
Wrap your bottle or can in a wet paper towel and place in the fridge. The drink will cool down much faster with the wet paper towel because of how heat is transferred. Normally, heat will transfer from a higher temperature object to a lower temperature object. In the case of the drink in the fridge, the heat will transfer from the soda can (higher temperature) to the air in the fridge (lower temperature). Heat can be more easily transferred through a solid like the soda can because the atoms are closer together on average. It is much more difficult with a gas like the air in the fridge because the atoms are more spread out on average. When we put a wet paper towel onto the outside of the can, we are using a liquid to facilitate the transfer of heat more easily than with air. Water from the towel will evaporate from the towel and the remaining water will be cooler. This process is called evaporative cooling. The wet towel also conducts the heat from the can cooling the soda to the temperature you prefer.

Option 2: The Salt & Ice Water Method.
Fill a bowl with ice and water, then pour salt over the icy mixture. Place the can or bottle in the bowl, and stir. It should be colder in about 5 minutes. The reason that this method works so well is trifold. First, you are lowering the melting point of the ice when you add salt so the mixture will be colder than 32° F. Basically as the ice is melting, it is using up a little bit of energy to break bonds causing the remaining water to be colder. Having a colder liquid helps the heat transfer between the liquid and the soda can. Which brings me to the second reason that it cools quickly – it’s a liquid! As we mentioned in option 1, heat can be transferred more easily through water than through air, so the water is facilitating the heat transfer. Lastly, stirring the bottle or can around in the mixture can reduce the amount of time needed to cool down the soda. If you did not stir the mixture, then the can would slowly transfer heat to the liquid surrounding it making the liquid immediately surrounding it warmer. The transfer of heat would continue slowly until both the can and the liquid reach equilibrium. By stirring the mixture, you are exposing the can to more of the cold water which speeds up the transfer of heat. In both situations, the can and liquid are reaching equilibrium, but over different amounts of time.

With either cooling option, you will get a nice cold beverage quickly and now you know the science behind it!

Have Science Fun in the Summer Sun with a Solar Print Kit!

by Marina Torres

Texas heat is here, and school’s out for summer. With all that bright sun outside, it’s a great time to play under the open sky. In the spirit of the season, we took science outside with a do-it-yourself kit from our own Museum Store. This super fun and educational solar print kit really leaves an impression! With this kit, you can challenge your children’s imagination and keep them active.

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Here’s what it comes with:12 five-by-seven pieces of solar paper, two print frame holders, two pre-printed stencil sheets and three blank note cards with envelopes so kids can share their finished projects with friends and families.

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And here’s how it works: First, lay everything out.

Cut out the pre-printed stencil images and gather the items you’d like to use in your image. In a dim room, place the solar sheet (located inside the black envelope) under the frame, with the blue side facing up. Place the items on top of the sheet and close the frame.

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Carefully place the system under the bright summer sun for about three minutes or until the sheet turns white.

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Gather your items and prints out of the sun, then rinse under running water and let them dry.

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Voila! You’ve merged art and science into one, and created these super cool solar images!

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Visit the Museum Store or shop online for this solar print kit and other DIY kits or browse around for other summer toys. We’ve also opened an exciting new Cabinet of Curiosities section inspired by our newest exhibition. There’s never been a better time to start your own collection!

Editor’s Note: Marina is the Visual Manager for the Houston Museum of Natural Science Museum Store.

Kids Explore STEAM Careers with HMNS Outreach

Inspiring a child takes effort, time, passion and heart. It’s why we do what we do.

At the Houston Museum of Natural Science, discoveries are made daily. The sounds of learning fill our hallways every day, from the gasp of wonder from a kid stepping onto the Morian Overlook for the first time or the squeal of delight as a butterfly in the Cockrell Butterfly Center rests on a child’s shoulder. Those sounds are all the evidence we need to know we are upholding HMNS’ mission, its commitment to education.

For the kids that may not be able to get to the museum, there is HMNS Outreach. Our variety of programs brings HMNS straight to the community, visiting hundreds of schools and organizations each year and reaching more than 100,000 children in 2015 alone. The ultimate goal is to instill in these kids a love of learning that will carry them to new heights in their careers and throughout their lives.

Here are some of the many STEAM careers that HMNS Outreach can inspire a child to reach for.

Veterinarian

The TOTAL Wildlife On Wheels offers an extraordinary look at animals of all kinds. Students get an up close and personal encounter with wildlife ranging from snakes and frogs to birds and mammals.

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Students in Turner High School’s Vet Tech program observe the wing of a Ringneck Dove, which travels as part of the TOTAL Wildlife On Wheels Vertebrates program.

Forensic Scientist

A presentation of Cleanup Crew from the Bugs On Wheels program will cover the process of decomposition and the return of vital elements to the Earth. These principles of decomposition are crucial to forensic scientists, who use arthropods and fungi to study crime scenes and gather more information.

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Entomologist Erin Mills shows off a Giant African Millipede during a presentation of the Bugs On Wheels program Cleanup Crew.

Physician

Body Works is our newest set of programs in the Science Start family, and these presentations focus on the anatomy and capabilities of the human body. From the brain to the heart to the skeleton, each of these presentations will provide students with a comprehensive overview of what we can do with what we’ve got.

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Geologist

A Chevron Earth Science On Wheels program like Know Your Rocks is immensely useful for future careers in Geology. A students’ knowledge of the rock cycle and the differences between different types of rocks and fuels can be vital in fields such as the energy industry.

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A student discusses the properties of two different specimens with his classmates during a presentation of Know Your Rocks.

Astronomer

A visit from the HMNS Discovery Dome includes more than 40 different shows about a range of topics, including a classic planetarium show, The Starry Night. One of today’s kids could discover a new planet, a galaxy, or even a black hole, and the Dome provides a great foundation for an interest in astronomy.

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Students at Reagan High School file into the Discovery Dome for a screening of Cosmic Collisions, a show narrated by Robert Redford about different outer space encounters between celestial objects.

Anthropologist

An interest in foreign cultures can take you all over the world or even back in time. Anthropologists study the history of humanity, and Docents To Go programs such as Native Americans or Ancient Egypt provide students with an introduction to different communities and societies.

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Volunteer Bob Joyce shows an arrowhead and arrow used for hunting by Native Americans.

Chemist

Try a ConocoPhillips Science On Stage program like Cool Chemistry, which discusses different chemical reactions as well as the properties of polymers and liquid nitrogen. It’s a great glimpse into what chemistry is all about!

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Educator Carolyn Leap discusses the properties of a polymer during a presentation of Cool Chemistry.

Artist

Students at Johnston Middle School have had the opportunity to sketch animals from the museum’s TOTAL Wildlife On Wheels and Bugs On Wheels programs over the years, and they’ve produced some spectacular pieces, like the crocodile skull below.

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These are just a few of the many STEAM careers that are natural extensions of the concepts discussed in HMNS Outreach. We are proud to play an important role in the lives of students all over the Houston area and beyond, and we are honored to have the opportunity to inspire the next generation.

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A student draws Peanut, a Costa Rican Curly Hair Tarantula, as Peanut cooperatively sits still.

To book HMNS Outreach, email outreach@hmns.org, call us at the number listed on our site, or fill out this form online. We look forward to working with you!

Use Science to “Hack” Your Big Idea this Weekend at HMNS!

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Calling all particle physicists, designers, open source ninjas, molecular biologists, students, programmers, and rocket scientists to join forces at Science Hack Day Houston 2016, hosted by the Houston Museum of Natural Science!

Science Hack Day Houston is an overnight marathon event from April 2 to 3, open to anyone excited about making things through science. Join us to make, “hack” or invent cool things in an inspiring environment. All it takes is dedication and an insatiable curiosity. No experience necessary, but there is a catch — you and your team must race the clock to complete an experimental prototype within 30 consecutive hours.

Check out the full event schedule for more details, then use the map on the HMNS web site to find us. We suggest the HMNS Garage for all-weekend, overnight parking. We will give participants a coupon with a discount for this garage. For free three-hour parking, you can park at the Garden Center Lot or the Houston Zoo lots. Don’t forget public transit! A ticket on the MetroRail costs $1.25, and the museum is an eight-minute walk from the Hermann Park/Rice University station.

Science Hack Day is a hack-a-thon with a twist — anyone interested in science can share their thoughts, find a team, and form multidisciplinary teams of between two and five individuals to learn something new, have fun, and create a mind-blowing prototype within 30 hours. The idea is to mash up ideas, mediums, industries and people to spark inspiration for future collaborations. When participants arrive, there will be a few speakers and an hour of brainstorming and proposing hack ideas. You can pitch ideas, or join up with projects you’re interested in. After that, teams are free to get to work on their hacks. On Sunday afternoon, everyone will reconvene to check out the hacks and award prizes to the favorites. Registration is free for individuals and teams.

The Hacks: Have a great project in mind? Science Hack Day is a great place to work with eager Houstonians with all sorts of skills and hobbies to bring your ideas to life. It’s okay if you don’t arrive with hack ideas; we need all the creative minds we can find to help contribute in whatever way they can.

What to Bring: 

  1. Bring your laptop and charger and/or anything you would like to hack. We will have some gadgets you can borrow to hack.
  2. Do not bring food or beverages. We will provide all meals. Please take a look at the schedule. If you have dietary restrictions, please contact the SHDH committee.
  3. Bring a sweater – the museum can get very cold.
  4. You must bring a guardian if you are underage.

For the (Optional) Sleepover:

  1. Bring a sleeping bag, a cover and a sleeping pad. The floor at the museum is hard and cold, so prepare for those conditions.
  2. Bring a sleeping mask. Most lights will be on through the night.
  3. Bring some toiletries. It feels nice to change out your contacts and brush your teeth.
  4. Bring a change of clothes to feel fresh for the next day. You’ll feel better.

For more information please go to ScienceHackDayHouston.com.