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Visualizing the Gravitational Pull of the Planets

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    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)
    Mercury0.334,8795,4273.74.3
    Venus4.8712,1045,2438.910.4
    Earth5.9712,7565,5149.811.2
    Moon0.0733,4753,3401.62.4
    Mars0.6426,7923,9333.75.0
    Jupiter1,898142,9841,32623.159.5
    Saturn568120,5366879.035.5
    Uranus86.851,1181,2718.721.3
    Neptune10249,5281,63811.023.5
    Pluto0.01462,3702,0950.71.3

    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.


    Gravity Assist

    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!

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Misc

Ranked: America’s Best Universities

Evaluated on 19 different metrics, here’s the list of America’s best universities, led by 14 private schools.

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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.

RankSchool NameStateTuition
1Princeton UniversityNew Jersey$59,710
2Massachusetts
Institute of
Technology
Massachusetts$60,156
3Harvard UniversityMassachusetts$59,076
3Stanford UniversityCalifornia$62,484
5Yale UniversityConnecticut$64,700
6University of
Pennsylvania
Pennsylvania$66,104
7California Institute
of Technology
California$63,255
7Duke UniversityNorth Carolina$66,172
9Brown UniversityRhode Island$68,230
9Johns Hopkins
University
Maryland$63,340
9Northwestern UniversityIllinois$65,997
12Columbia UniversityNew York$65,524
12Cornell UniversityNew York$66,014
12University of ChicagoIllinois$65,619
15University of
California, Berkeley
California$48,465 (out-state)
$15,891 (in-state)
15University of
California, LA
California$46,326 (out-state)
$13,752 (in-state)
17Rice UniversityTexas$58,128
18Dartmouth CollegeNew Hampshire$65,511
18Vanderbilt UniversityTennessee$63,946
20University of Notre DameIndiana$62,693
21University of
Michigan, Ann Arbor
Michigan$57,273 (out-state)
$17,786 (in-state)
22Georgetown UniversityWashington, DC$65,082
22University of North
Carolina at Chapel Hill
North Carolina$39,338 (out-state)
$8,998 (in-state)
24Carnegie Mellon UniversityPennsylvania$63,829
24Emory UniversityGeorgia$60,774
24University of VirginiaVirginia$58,950 (out-state)
$22,323 (in-state)
24Washington
University, St. Louis
Missouri$62,982
28University of
California, Davis
California$46,043 (out-state)
$15,266 (in-state)
28University of
California, San Diego
California$48,630 (out-state)
$16,056 (in-state)
28University of FloridaFlorida$28,658 (out-state)
$6,381 (in-state)
28University of
Southern California
California$68,237
32University of
Texas, Austin
Texas$41,070 (out-state)
$11,698 (in-state)
33Georgia Institute
of Technology
Georgia$32,876 (out-state)
$11,764 (in-state)
33University of
California, Irvine
California$47,759 (out-state)
$15,185 (in-state)
35New York UniversityNew York$60,438
35University of
California, Santa
Barbara
California$45,658 (out-state)
$14,881 (in-state)
35University of Illinois
Urbana-Champaign
Illinois$36,068 (out-state)
$17,572 (in-state)
35University of
Wisconsin, Madison
Wisconsin$40,603 (out-state)
$11,205 (in-state)
39Boston CollegeMassachusetts$67,680
40Rutgers University,
New Brunswick
New Jersey$36,001 (out-state)
$17,239 (in-state)
40Tufts UniversityMassachusetts$67,844
40University of WashingtonWashington$41,997 (out-state)
$12,643 (in-state)
43Boston UniversityMassachusetts$65,168
43The Ohio State UniversityOhio$36,722 (out-state)
$12,485 (in-state)
43Purdue University,
Main Campus
Indiana$28,794 (out-state)
$9,992 (in-state)
46University of
Maryland, College
Park
Maryland$40,306 (out-state)
$11,505 (in-state)
47Lehigh UniversityPennsylvania$62,180
47Texas A&M UniversityTexas$40,607 (out-state)
$12,413 (in-state)
47University of GeorgiaGeorgia$30,220 (out-state)
$11,180 (in-state)
47University of RochesterNew York$64,384
47Virginia TechVirginia$36,090 (out-state)
$15,478 (in-state)
47Wake Forest UniversityNorth Carolina$64,758
53Case Western
Reserve University
Ohio$62,234
53Florida State UniversityFlorida$21,683 (out-state)
$6,517 (in-state)
53Northeastern UniversityMassachusetts$63,141
53University of
Minnesota, Twin
Cities
Minnesota$36,402 (out-state)
$16,488 (in-state)
53William & MaryVirginia$48,841 (out-state)
$25,041 (in-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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