In science, scale can be difficult to judge, particularly when coming across an image of science without any proper context. Is this fascinating object something that I can hold in my hand, find under a microscope, or does it reach across the galaxy? It’s important — and quite interesting — to learn about objects on every scale. After all, some processes can be similar whether they’re on a micro or macro scale.
Remarkably, some of the images of the very small look astonishingly like those of the very big. In this visual essay, we compare some size doppelgangers and begin to explore the true scale of science.
We often think of the Earth as large — and it is compared to things on the human scale. Yet, a million Earths can fit inside our Sun, which is very small compared to many other objects in space. Likewise, we generally think of grains of sand as being incredibly small in contrast to experiences in our everyday lives. However, the realm of cellular and molecular biology and its constituents, for example, are much smaller than that sand grain and impossible for the unaided eye to see.
The simple question of “how big is this?” often turns out to be not so simple to answer. We can explore this idea of scale through the imagery that different disciplines of science generate. In these images of both the large and the very small, we can find patterns, identify color (which is typically applied during the image-making process), and examine texture. Despite their disparate subject matters, these images possess many similarities and offer an opportunity to explore the wonders and beauty of science from “micro” to “macro”.
(Mouse over the images at right to learn more about each object)
We might frequently ask how wide or how long something is. The concept of length is familiar to us for things we encounter here on Earth. One way to describe it is as the distance between two points. When we think about objects on different scales, we find that distances can stretch (or shrink) almost as far as our imaginations. Typically, the units for length are shown in meter (m), or kilometers (km, which equals 1000 meters)) for those using the metric system. In the US, most feel comfortable when dealing with feet and miles. In astronomy, distances and sizes, however, are often too big for the mile or km once you move outside of the objects in our solar system. Instead, cosmic objects and distances are measured in units of light years, where one light year is the distance that light travels in a year—about 10 trillion kilometers. In microscopy, we must go to the other end of the size spectrum and measure in micrometers (also called a micron, which is about one-millionth of a meter) or nanometers (where one nanometer is one-billionth of a meter). In this piece, we’ve provided most objects in meters or kilometers so you can easily compare their sizes.
When a satellite observes an object in space, its camera records photons. These photons come down from the spacecraft coded in the form of 1’s and 0’s. Scientific software then translates that data into an event table that contains the time, energy and position of each photon that struck the detector during the observation. The data is further processed with software to form the visual representation of the object.
The terms "false color" or "representative color" are often used to describe astronomy images whose colors represent measured intensities outside the visible portion of the electromagnetic spectrum (for X-ray light, for example). A representative color image is not wrong or fake — it’s a selection of colors chosen to represent a characteristic of the image (e.g., intensity, energy or chemical composition). For example, a chromatic ordering can be made by applying red, green and blue colors to the low, medium and high energy cuts of the data. The colors used are representative of the physical processes underlying the objects in the image.
Similarly, in microscopy, scientists also have to apply color to many of their samples. There are many different techniques and purposes, from the microscope used, to any staining technique of the samples themselves. A scanning electron microscope (SEM), for example, conducts a patterned scan over the object being studied, using a highly focused beam of electrons. When the surface is struck, signals are produced, such as X-rays or visible light. The signals then bounce back to the microscope and recreate that part of the object as a visual representation. Similarly to our astronomical images, the sensitivity of the equipment goes well beyond human vision. So, color is applied by mapping the energy cuts. In this activity, some of the images have been adapted from their original color schemes to closer connect with their image pair, for the purpose of visual comparison only, and not in relation to the science.