Visualizing the Gravitational Pull of the Planets
Gravity is one of the basic forces in the universe. Every object out there exerts a gravitational influence on every other object, but to what degree?
The gravity of the sun keeps all the planets in orbit in our solar system. However, each planet, moon and asteroid have their own gravitational pull defined by their density, size, mass, and proximity to other celestial bodies.
Dr. James O’Donoghue, a Planetary Astronomer at JAXA (Japan Aerospace Exploration Agency) created an animation that simplifies this concept by animating the time it takes a ball to drop from 1,000 meters to the surface of each planet and the Earth’s moon, assuming no air resistance, to better visualize the gravitational pull of the planets.
Sink like a Stone or Float like a Feather
Now, if you were hypothetically landing your spacecraft on a strange planet, you would want to know your rate of descent. Would you float like a feather or sink like a stone?
It is a planet’s size, mass, and density that determines how strong its gravitational pull is, or, how quick or slow you will approach the surface.
|Mass (1024kg)||Diameter (km)||Density (kg/m3)||Gravity (m/s2)||Escape Velocity (km/s)|
According to Dr. O’Donoghue, large planets have gravity comparable to smaller ones at the surface—for example, Uranus attracts the ball down slower than on Earth. This is because the relatively low average density of Uranus puts the actual surface of the planet far away from the majority of the planet’s mass in the core.
Similarly, Mars is almost double the mass of Mercury, but you can see the surface gravity is actually the same which demonstrates that Mercury is much denser than Mars.
Exploring the Outer Reaches: Gravity Assistance
Knowing the pull of each of the planets can help propel space flight to the furthest extents of the solar system. The “gravity assist” flyby technique can add or subtract momentum to increase or decrease the energy of a spacecraft’s orbit.
Generally it has been used in solar orbit, to increase a spacecraft’s velocity and propel it outward in the solar system, much farther away from the sun than its launch vehicle would have been capable of doing, as in the journey of NASA’s Voyager 2.
Launched in 1977, Voyager 2 flew by Jupiter for reconnaissance, and for a trajectory boost to Saturn. It then relied on a gravity assist from Saturn and then another from Uranus, propelling it to Neptune and beyond.
Despite the assistance, Voyager 2’s journey still took over 20 years to reach the edge of the solar system. The potential for using the power of gravity is so much more…
Tractor Beams, Shields, and Warp Drives…Oh My!
Imagine disabling an enemy starship with a gravity beam and deflecting an incoming photon torpedo with gravity shields. It would be incredible and a sci-fi dream come true.
However, technology is still 42 years from the fictional date in Star Trek when mankind built the first warp engine, harnessing the power of gravity and unlocking the universe for discovery. There is still time!
Currently, the ALPHA Experiment at CERN is investigating whether it is possible to create some form of anti-gravitational field. This research could create a gravitational conductor shield to counteract the forces of gravity and allow the creation of a warp drive.
By better understanding the forces that keep us grounded on our planets, the sooner we will be able to escape these forces and feel the gravitational pull of the planets for ourselves.
…to boldly go where no one has gone before!
Ranked: America’s Best Universities
Evaluated on 19 different metrics, here’s the list of America’s best universities, led by 14 private schools.
Ranked: America’s Best Universities
The latest ranking of America’s best universities is here, perfectly timed for the approaching admissions season.
“Best” is of course subjective, and U.S. News and World Report has compiled 19 metrics on which they evaluated more than 400 national universities. Some of them include:
- Graduation rates & performance: A four-year rolling average of the proportion of each entering class earning a bachelor’s degree in six years or less. Performance is measured against predictions made by the publishers, and when beaten, the university gains a higher scoring.
- Peer assessment: A two-year weighted average of ratings from top academics—presidents, provosts and deans of admissions—on academic quality of peer institutions with which they are familiar.
- Financial resources: The average per student spend on instruction, research, student services and related educational expenditures in the 2021 fiscal year.
- Debt: A school’s average accumulated federal loan debt among borrowers only.
- Pell graduation rates & performance: the same calculation as stated above, but focused only on Pell Grant students, adjusted to give more credit to schools with larger Pell student proportions.
The website’s methodology section details how they sourced their data, the weights assigned to each metric, and their changes over the years.
From the hundreds assessed come the nearly 50 best universities that offer a variety of undergraduate majors, post-graduate programs, emphasize research, or award professional practice doctorates.
Which are the Best Universities in America?
At the top of the list, Princeton University is the best university in the country, known for its physics, economics, and international relations departments. Notably, it’s a rare Ivy league university that does not have a law, medical, or business school.
Here’s the full ranking of America’s best universities, along with annual tuition requirements.
|1||Princeton University||New Jersey||$59,710|
|7||Duke University||North Carolina||$66,172|
|9||Brown University||Rhode Island||$68,230|
|12||Columbia University||New York||$65,524|
|12||Cornell University||New York||$66,014|
|12||University of Chicago||Illinois||$65,619|
|18||Dartmouth College||New Hampshire||$65,511|
|20||University of Notre Dame||Indiana||$62,693|
Michigan, Ann Arbor
|22||Georgetown University||Washington, DC||$65,082|
|22||University of North|
Carolina at Chapel Hill
|North Carolina||$39,338 (out-state)
|24||Carnegie Mellon University||Pennsylvania||$63,829|
|24||University of Virginia||Virginia||$58,950 (out-state)
University, St. Louis
California, San Diego
|28||University of Florida||Florida||$28,658 (out-state)
|35||New York University||New York||$60,438|
|35||University of Illinois|
|New Jersey||$36,001 (out-state)
|40||University of Washington||Washington||$41,997 (out-state)
|43||The Ohio State University||Ohio||$36,722 (out-state)
|47||Texas A&M University||Texas||$40,607 (out-state)
|47||University of Georgia||Georgia||$30,220 (out-state)
|47||University of Rochester||New York||$64,384|
|47||Virginia Tech||Virginia||$36,090 (out-state)
|47||Wake Forest University||North Carolina||$64,758|
|53||Florida State University||Florida||$21,683 (out-state)
|53||William & Mary||Virginia||$48,841 (out-state)
MIT places second, and Harvard and Stanford tie for third. Yale rounds out the top five.
Private universities, including seven Ivy League colleges, dominate the top of the rankings. Meanwhile, the highest-ranked public schools are tied at 15th, both state schools in California.
For affordability, since the higher ranks are populated by private universities, there tends to be a broad correlation of better universities being more expensive. That said, the most expensive school in the top 50 ranks is actually the University of Southern California, tied at 28th, for $68,237/year.
As it happens, also tied at 28th, the University of Florida is the most affordable public school for in-state students ($6,381/year) and Florida State University tied at 53rd, is the most affordable for out-of-staters at $21,683/year.
However these costs are tuition-only, and don’t account for other necessary expenses: accommodation, food, and textbooks.
Best University versus Best “Fit”
Finding the best university for prospective students is more than just perusing a long ranking list.
Aside from the numerous schools present within each university—which can often be the best for specific majors—factors like location, proximity to family, campus culture, the non-academic pursuits (sports, extracurriculars, internships) are also taken into consideration.
In fact, research has found that just attaining a university degree improves future earnings potential and employability.
Furthermore, individual engagement at college (irrespective of the rank of the school in question) plays a far bigger role in learning and general well-being than simply attending a highly-ranked school.
However, for low income and minority students, attending a top-ranked school does improve future earnings considerably. For women, it also often results in delaying marriage and kids, which results in more work-hours and as a result, more pay.
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