4th Dimension!

A hypercube moving along the 4D axis

A 4D torus rotating on the 4D axis.

4D, meaning the 4 common dimensions, is an important idea in physics referring to three-dimensional space (3D), which adds the dimension of time to the other three dimensions of length, width, and depth. In geometry, the fourth dimension is related to the other three dimensions by imagining another direction through space; just as the dimension of depth can be added to a squareto create a cube, the fourth dimension can be added to a cube to create a hypercube.

In mathematics, four-dimension space is an abstract concept which has been studied by mathematics and philosophers for many years. Mathematicians who studied four-dimension space in the 19th century include Möbius, Schläfi, Bernhard Riemann, and Charles Howard Hinton.

In the 20th century, the idea of spacetime was developed by Albert Einstein, connecting space and time together. The difference is that spacetime is not a Euclidean space, but instead is called "Minkowski spacetime".

UFO

An unidentified flying object or "UFO" is an object perceived in the sky that is not readily identified. Most UFOs are later identified as conventional objects or phenomena. The term is widely used for claimed observations of extraterrestrial craft.

Nasa's planet hunter on its way to orbit

NASA’s next planet-hunter, the Transiting Exoplanet Survey Satellite (TESS), successfully launched on a SpaceX Falcon 9 on April 18, 2018. TESS will search for new worlds outside our solar system for further study. Credit: SpaceX

NASA’s Transiting Exoplanet Survey Satellite (TESS) launched on the first-of-its-kind mission to find worlds beyond our solar system, including some that could support life.

TESS, which is expected to find thousands of new exoplanets orbiting nearby stars, lifted off at 6:51 p.m. EDT Wednesday on a SpaceX Falcon 9 rocket from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida. At 7:53 p.m., the twin solar arrays that will power the spacecraft successfully deployed.

“We are thrilled TESS is on its way to help us discover worlds we have yet to imagine, worlds that could possibly be habitable, or harbor life,” said Thomas Zurbuchen, associate administrator of NASA’s Science Mission Directorate in Washington. “With missions like the James Webb Space Telescope to help us study the details of these planets, we are ever the closer to discovering whether we are alone in the universe.”

Over the course of several weeks, TESS will use six thruster burns to travel in a series of progressively elongated orbits to reach the Moon, which will provide a gravitational assist so that TESS can transfer into its 13.7-day final science orbit around Earth. After approximately 60 days of check-out and instrument testing, the spacecraft will begin its work.

A SpaceX Falcon 9 rocket soars upward after lifting off from Space Launch Complex 40 at Cape Canaveral Air Force Station in Florida, carrying NASA's Transiting Exoplanet Survey Satellite (TESS). Liftoff was at 6:51 p.m. EDT. TESS will search for planets outside of our solar system. The mission will find exoplanets that periodically block part of the light from their host stars, events called transits. The satellite will survey the nearest and brightest stars for two years to search for transiting exoplanets. Credit: NASA/Kim Shiflett

“One critical piece for the science return of TESS is the high data rate associated with its orbit,” said George Ricker, TESS principal investigator at the Massachusetts Institute of Technology’s (MIT) Kavli Institute for Astrophysics and Space Research in Cambridge. “Each time the spacecraft passes close to Earth, it will transmit full-frame images taken with the cameras. That’s one of the unique things TESS brings that was not possible before.”

For this two-year survey mission, scientists divided the sky into 26 sectors. TESS will use four unique wide-field cameras to map 13 sectors encompassing the southern sky during its first year of observations and 13 sectors of the northern sky during the second year, altogether covering 85 percent of the sky.

TESS will be watching for phenomena called transits. A transit occurs when a planet passes in front of its star from the observer’s perspective, causing a periodic and regular dip in the star’s brightness. More than 78 percent of the approximately 3,700 confirmed exoplanets have been found using transits.

NASA’s Kepler spacecraft found more than 2,600 exoplanets, most orbiting faint stars between 300 and 3,000 light-years from Earth, using this same method of watching for transits. TESS will focus on stars between 30 and 300 light-years away and 30 to 100 times brighter than Kepler’s targets.

The brightness of these target stars will allow researchers to use spectroscopy, the study of the absorption and emission of light, to determine a planet’s mass, density and atmospheric composition. Water, and other key molecules, in its atmosphere can give us hints about a planets’ capacity to harbor life.

“The targets TESS finds are going to be fantastic subjects for research for decades to come,” said Stephen Rinehart, TESS project scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s the beginning of a new era of exoplanet research.”

Through the TESS Guest Investigator Program, the worldwide scientific community will be able to conduct research beyond TESS’s core mission in areas ranging from exoplanet characterization to stellar astrophysics, distant galaxies and solar system science.

TESS is a NASA Astrophysics Explorer mission led and operated by MIT and managed by Goddard. George Ricker, of MIT’s Kavli Institute for Astrophysics and Space Research, serves as principal investigator for the mission. TESS’s four wide-field cameras were developed by MIT’s Lincoln Laboratory. Additional partners include Orbital ATK, NASA’s Ames Research Center, the Harvard-Smithsonian Center for Astrophysics, and the Space Telescope Science Institute. More than a dozen universities, research institutes and observatories worldwide are participants in the mission.

For more information on TESS, go to:

https://www.nasa.gov/tess

Paint it black!

NASA's Hubble captures blistering pitch-black planet

This illustration shows one of the darkest known exoplanets — an alien world as black as fresh asphalt — orbiting a star like our Sun. Credit: NASA/ESA/G. Bacon (STScI)

The oddball exoplanet, called WASP-12b, is one of a class of so-called "hot Jupiters," gigantic, gaseous planets that orbit very close to their host star and are heated to extreme temperatures. The planet's atmosphere is so hot that most molecules are unable to survive on the blistering day side of the planet, where the temperature is 4,600 degrees Fahrenheit. Therefore, clouds probably cannot form to reflect light back into space. Instead, incoming light penetrates deep into the planet's atmosphere where it is absorbed by hydrogen atoms and converted to heat energy.

Venus

Venus may have had a shallow liquid-water ocean and habitable surface temperatures for up to 2 billion years of its early history, according to computer modeling of the planet’s ancient climate by scientists at NASA’s Goddard Institute for Space Studies (GISS) in New York.

 Second planet from the Sun and our closest planetary neighbor, Venus is similar in structure and size to Earth, but it is now a very different world. Venus spins slowly in the opposite direction most planets do. Its thick atmosphere traps heat in a runaway greenhouse effect, making it the hottest planet in our solar system—with surface temperatures hot enough to melt lead. Glimpses below the clouds reveal volcanoes and deformed mountains.

10 Things to Know About Venus

1

EARTH-SIZED

If the sun were as tall as a typical front door, the Earth and Venus would each be about the size of a nickel.  

2

SECOND ROCK

Venus orbits our Sun, a star. Venus is the second closest planet to the sun at a distance of about 67 million miles (108 million km).

3

A DAY LONGER THAN A YEAR

One day on Venus lasts 243 Earth days because Venus spins backwards, with its sun rising in the west and setting in the east.HASING CLOUDS ON VENUS

4

DIVERSE TERRAIN

Venus' solid surface is a volcanic landscape covered with extensive plains featuring high volcanic mountains and vast ridged plateaus.

5

MOONLESS AND RINGLESS

Venus has no moons and no rings.

6

GREENHOUSE EFFECT

The planet’s surface temperature is about 900 degrees Fahrenheit (465 degrees Celsius)—hot enough to melt lead.

7

WATER ON VENUS

Many scientists believe water once existed on the surface. Future Venus explorers will search for evidence of an ancient ocean.

8

MANY VISITORS

More than 40 spacecraft have explored Venus. The ‘90s Magellan mission mapped the planet's surface and Akatsuki is currently orbiting Venus.

9

LIFE ON VENUS

Venus’ extreme temperatures and acidic clouds make it an unlikely place for life as we know it.

10

SUPER ROTATING ATMOSPHERE

While the surface rotates slowly, the winds blow at hurricane force, sending clouds completely around the planet every five days.

Mercury

Like the waistband of a couch potato in midlife, the orbits of planets in our solar system are expanding. It happens because the Sun’s gravitational grip gradually weakens as our star ages and loses mass. Recently, a team of NASA and MIT scientists indirectly measured the Sun's mass loss and other solar parameters by looking at changes in Mercury’s orbit.

 The smallest planet in our solar system and nearest to the Sun, Mercury is only slightly larger than Earth's moon. From the surface of Mercury, the Sun would appear more than three times as large as it does when viewed from Earth, and the sunlight would be as much as 11 times brighter. Despite its proximity to the Sun, Mercury is not the hottest planet in our solar system—that title belongs to nearby Venus—but it is the fastest, zipping around the Sun every 88 Earth days.

10 Things to Know About Mercury

1

SMALLEST

Mercury is the smallest planet in our solar system - only slightly larger than the Earth's moon. If the sun were as tall as a typical front door, Earth would be the size of a nickel and Mercury would be about as big as a green pea.

2

INSIDER

It is the closest planet to the sun at a distance of about 58 million km (36 million miles) or 0.39 AU.

3

LONG DAYS, SHORT YEARS

One day on Mercury (the time it takes for Mercury to rotate or spin once with respect to the stars) takes 59 Earth days. One day-night cycle on Mercury takes 175.97 Earth days. Mercury makes a complete orbit around the sun (a year in Mercury time) in just 88 Earth days.

4

ROUGH SURFACE

Mercury is a rocky planet, also known as a terrestrial planet. Mercury has a solid, cratered surface, much like the Earth's moon.

5

CAN'T BREATHE IT

Mercury's thin atmosphere, or exosphere, is composed mostly of oxygen (O2), sodium (Na), hydrogen (H2), helium (He), and potassium (K). Atoms that are blasted off the surface by the solar wind and micrometeoroid impacts create Mercury's exosphere.

6

MOONLESS

Mercury has no moons. 

7

RINGLESS

There are no rings around Mercury. 

8

TOUGH PLACE TO LIVE

No evidence for life has been found on Mercury. Daytime Temperatures can reach 430 degrees Celsius (800 degrees Fahrenheit) and drop to -180 degrees Celsius (-290 degrees Fahrenheit) at night. It is unlikely life (as we know it) could survive on this planet.

9

BIG SUN

Standing on Mercury's surface at its closest point to the sun, the sun would appear more than three times larger than it does on Earth.

10

ROBOTIC VISITORS

Only two missions have visited this rocky planet: Mariner 10 in 1974-5 and MESSENGER, which flew past Mercury three times before going into orbit around Mercury in 2011.

The Solar System

The Solar System^[a] is the gravitationallybound system comprising the Sun and the objects that orbit it, either directly or indirectly.^[b] Of those objects that orbit the Sun directly, the largest eight are the planets,^[c] with the remainder being smaller objects, such as dwarf planets and small Solar System bodies. Of the objects that orbit the Sun indirectly, the moons, two are larger than the smallest planet, Mercury.^[d]

Solar System

The Sun and planets of the Solar System (distances not to scale)
Age	4.568 billion years
Location	Local Interstellar Cloud, Local Bubble, Orion–Cygnus Arm, Milky Way
System mass	1.0014 Solar masses
Nearest star	Proxima Centauri  (4.22ly) Alpha Centauri (4.37 ly)
Nearest knownplanetary system	Proxima Centaurisystem  (4.25 ly)
Semi-major axis of outer known planet (Neptune)	30.10 AU  (4.503 billion km)
Distance to Kuiper cliff	50 AU
Populations
Stars	1  (Sun)
Known planets	8 (Mercury   Venus   Earth   Mars   Jupiter   Saturn   Uranus   Neptune)
Known dwarf planets	Possibly several hundred;[1] five currently recognized by the IAU (Ceres   Pluto   Haumea   Makemake   Eris)
Known natural satellites	472 (175 planetary[2]   297 minor planetary[3])
Known minor planets	707,664  (as of 2016-03-07)[4]
Known comets	3,406  (as of 2016-03-07)[4]
Identified rounded satellites	19
Invariable-to-galactic plane inclination	60.19°  (ecliptic)
Distance to Galactic Center	27,000 ± 1,000 ly
Orbital speed	220 km/s
Orbital period	225–250 Myr
Spectral type	G2V
Frost line	≈5 AU[5]
Distance to heliopause	≈120 AU
Hill sphere radius	≈1–3 ly

The Solar System formed 4.6 billion years ago from the gravitational collapse of a giant interstellar molecular cloud. The vast majority of the system's mass is in the Sun, with the majority of the remaining mass contained in Jupiter. The four smaller inner planets, Mercury, Venus, Earth and Mars, are terrestrial planets, being primarily composed of rock and metal. The four outer planets are giant planets, being substantially more massive than the terrestrials. The two largest, Jupiter and Saturn, are gas giants, being composed mainly of hydrogen and helium; the two outermost planets, Uranus and Neptune, are ice giants, being composed mostly of substances with relatively high melting points compared with hydrogen and helium, called volatiles, such as water, ammonia and methane. All eight planets have almost circular orbits that lie within a nearly flat disc called the ecliptic.

The Solar System also contains smaller objects.^[e] The asteroid belt, which lies between the orbits of Mars and Jupiter, mostly contains objects composed, like the terrestrial planets, of rock and metal. Beyond Neptune's orbit lie the Kuiper belt and scattered disc, which are populations of trans-Neptunian objects composed mostly of ices, and beyond them a newly discovered population of sednoids. Within these populations are several dozen to possibly tens of thousands of objects large enough that they have been rounded by their own gravity.^[10] Such objects are categorized as dwarf planets. Identified dwarf planets include the asteroid Ceres and the trans-Neptunian objects Pluto and Eris.^[e] In addition to these two regions, various other small-body populations, including comets, centaurs and interplanetary dust clouds, freely travel between regions. Six of the planets, at least four of the dwarf planets, and many of the smaller bodies are orbited by natural satellites,^[f] usually termed "moons" after the Moon. Each of the outer planets is encircled by planetary rings of dust and other small objects.

The solar wind, a stream of charged particles flowing outwards from the Sun, creates a bubble-like region in the interstellar mediumknown as the heliosphere. The heliopause is the point at which pressure from the solar wind is equal to the opposing pressure of the interstellar medium; it extends out to the edge of the scattered disc. The Oort cloud, which is thought to be the source for long-period comets, may also exist at a distance roughly a thousand times further than the heliosphere. The Solar System is located in the Orion Arm, 26,000 light-years from the center of the Milky Way.