Chart assignment
Charts to read and discuss
Read each chart, then answer its questions. Every chart shows its source and date; open it for a table of the numbers and the data to download.
Chart 1 of 3 · Space
What are the closest asteroid flybys ever recorded?
The interactive chart needs JavaScript. The numbers are on the chart's page.
As of November 2026, the closest known asteroid flyby was 2025 UC11 (Oct 30, 2025), about 228 km above Earth's surface; the International Space Station orbits about 400 km up. The 15 flybys here were by small rocks, roughly 1 to 10 meters across, and nearly all are recent, because only modern surveys can spot rocks that small. JPL measures from Earth's center, so the chart subtracts Earth's average radius (6,371 km); asteroids that hit Earth aren't counted.
Questions to discuss
- In one sentence of your own, what does this chart show?
- Find the biggest change or difference in the chart. What might explain it?
- Who collected these numbers, and how recent are they? What else would you want to know before drawing a conclusion?
Source: NASA/JPL Center for Near Earth Object Studies (CNEOS), SBDB Close Approach Data (Public domain (NASA data); credit NASA/JPL-Caltech CNEOS) · Data as of Nov 4, 2026
Open the chart and its numbersChart 2 of 3 · Energy
Where does US electricity come from?
The interactive chart needs JavaScript. The numbers are on the chart's page.
In 2025 natural gas made 40.8% of US electricity, followed by nuclear (17.7%) and coal (16.6%). Wind made 10.5% and solar 6.7%. Solar counts only utility-scale plants, not rooftop panels, and the 2025 figures are preliminary.
How to read this chart
Each bar is one energy source's share of all the electricity made in the U.S. in a year, so the bars add up to about 100%. The bars start at zero, so a bar twice as long means twice the share. Solar counts only large power plants, not panels on rooftops.
Questions to discuss
- Which source makes the most electricity? About how many times more than the smallest bar?
- Which of these sources burn fuel and which don't? What share of electricity comes from each group?
- Why might a chart of this kind look different in your state than for the whole country?
Source: U.S. Energy Information Administration, Monthly Energy Review (Table 7.2a) (Public domain (U.S. government work)) · Data as of Dec 31, 2025
Open the chart and its numbersChart 3 of 3 · Earthquakes
How much rarer is each step up in earthquake magnitude?
The interactive chart needs JavaScript. The numbers are on the chart's page.
In 2025 the world recorded 6,428 earthquakes of magnitude 4.5 to 4.9, 1,983 of magnitude 5, 129 of magnitude 6, 15 of magnitude 7 and 1 of magnitude 8 or more. Each step up in magnitude is roughly ten times rarer, and releases about 32 times more energy. Countless smaller quakes go unrecorded worldwide, so the chart starts at 4.5.
How to read this chart
Each bar counts the earthquakes recorded worldwide in one year within a range of magnitudes. The bars start at zero. Each whole step up in magnitude releases about 32 times more energy, so a magnitude 7 quake is far more than one step stronger than a 6.
Questions to discuss
- Roughly how many times more common is each band than the one above it?
- The biggest bars are hard to compare with the smallest ones on this scale. What other way could you show these numbers?
- The chart starts at magnitude 4.5. Why might smaller earthquakes around the world go uncounted?
Source: U.S. Geological Survey, ANSS Comprehensive Earthquake Catalog (ComCat) (Public domain (U.S. government work); source U.S. Geological Survey) · Data as of Dec 31, 2025
Open the chart and its numbersTeachers: make your own chart assignment, or change this one. Free, no account needed.