Today’s astronomers are busy building the census of extrasolar planets, which has reached a total of 4,884 confirmed planets, with another 8,288 candidates awaiting confirmation. Now that the James Webb Space Telescope (JWST) has finally been launched, future surveys will be reaching beyond mere discovery and will be focused more on characterization. In essence, future exoplanet surveys will determine with greater certainty which planets are habitable and which are not.
One characteristic that they will be on the lookout for in particular is the presence of planetary magnetic fields (aka. magnetospheres). On Earth, the atmosphere and all life on the surface are protected by a magnetic field, which is why they are considered crucial to habitability. Using data from the venerated Hubble Space Telescope (HST), an international team of astronomers reported the detection of a magnetic field around an exoplanet for the first time!
The outer “ice giant” planets, Neptune and Uranus, have plenty of mysteries. One of the biggest is where exactly they got their magnetic fields. They are strong at that, with Neptune’s being twenty-seven times more powerful than Earth’s, while Uranus’ varies between ? and four times Earth’s strength. Chaos rules in these electromagnetic environments, making them exceptionally hard to both understand and model. Now a team of researchers led by Dr. Vitali Prakpenka of the University of Chicago thinks they might have found the underlying cause of both the field’s strength and its randomness – “hot ice.”
Magnetic fields are great for lots of things – directing explorers, levitating trains, and containing nuclear fusion reactions are just an example of what these invisible forces can do. Now we can ascribe another feature to magnetic fields – they can give planets a rocky core.
For the first time astronomers have observed waves of magnetic energy, known as Alfvén waves, in the photosphere of the sun. This discovery may help explain why the solar corona is so much hotter than the surface.
White dwarfs have some surprisingly strong magnetic fields, and one team of astronomers may have finally found the reason why. When they cool, they can activate a dynamo mechanism similar to what powers the Earth’s magnetic field.
Every 200,000 to 300,000 years Earth’s magnetic poles reverse. What was once the north pole becomes the south, and vice versa. It’s a time of invisible upheaval.
The last reversal was unusual because it was so long ago. For some reason, the poles have remained oriented the way they are now for about three-quarters of a million years. A new study has revealed some of the detail of that reversal.
We recently observed the strongest magnetic field ever recorded in the Universe. The record-breaking field was discovered at the surface of a neutron star called GRO J1008-57 with a magnetic field strength of approximately 1 BILLION Tesla. For comparison, the Earth’s magnetic field clocks in at about 1/20,000 of a Tesla – tens of trillions of times weaker than you’d experience on this neutron star…and that is a good thing for your general health and wellbeing.
Neutron stars are the “dead cores” of once massive stars which have ended their lives as supernova. These stars exhausted their supply of hydrogen fuel in their core and a power balance between the internal energy of the star surging outward, and the star’s own massive gravity crushing inward, is cataclysmically unbalanced – gravity wins. The star collapses in on itself. The outer layers fall onto the core crushing it into the densest object we know of in the Universe – a neutron star. Even atoms are crushed. Negatively charged electrons are forced into the atomic nuclei meeting their positive proton counterparts creating more neutrons. When the core can be crushed no further, the outer remaining material of the star rebounds back into space in a massive explosion – a supernova. The resulting neutron star, made of the crushed stellar core, is so dense that a single sugar-cube-sized sampling would weigh billions of tons – as much as a mountain (though if you’re “worthy” you MIGHT able to lift it since Thor’s Hammer is made of the stuff). Neutron stars are typically about 20km in diameter and can still be a million degrees Kelvin at the surface.
But if they’re “dead,” how can neutron stars be some of the most magnetic and powerful objects in the Universe?
If you’ve ever used a compass, you know that the magnetic needle always points North. Well, almost North. If you just happen to be out camping for the weekend, the difference doesn’t matter. For scientists studying the Earth’s interior, the difference is important. How Earth’s magnetic field changes over time give us clues about how our planet generates a magnetic field in the first place.
The North Pole ain’t what it used to be. Well, the geographic North Pole stays fixed over time (mostly because we define it to stay fixed over time) but the magnetic north pole constantly moves. And over the past decade it’s been moving out of Canada towards Siberia four times faster than it has in the past couple centuries. Armed with data from the ESA’s Swarm satellite, scientists might finally know why: the shifting of our magnetic field north pole is caused by a titanic struggle between two competing massive magnetic plumes.