The “Heliophysics Big Year” was an extended “year” when major solar events engaged the public. NASA and the National Science Foundation (NSF) funded several projects to educate the public on the science of the heliosphere and safe observing practices. In response to this initiative, we worked with other teams to create and disseminate accurate yet engaging information. We expanded our eclipse website (https://space.rice.edu/eclipse/) with activities, citizen science projects, resources, training videos, suggested equipment, and links to other compendia. We directed the Citizen CATE 2024 project, and trained state coordinators and their teams to use the specialized equipment and procedures. We trained teachers at local, regional, national, and international workshops, providing eclipse viewing cards, lenses for making “solar cup projectors,” a pattern for a safe viewing screen, and additional materials. With other teams, we gave presentations to the media at SciLine in San Antonio and hosted public events to demonstrate safe eclipse viewing techniques. The most lasting and impactful product was our planetarium show “Totality,” which was distributed free of license fees. More than 180,000 views of the show and its animations have been documented. We improved our space weather forecasting site (https://mms.rice.edu) and used our email lists (14,000+) to send out real-time warnings about the major solar storm of 10–11 May 2024. In total, we provided nearly two million people with heliophysics information. In summary, the federal/private/business partnerships meant that the events of this “year” were a fun, safe, learning experience for tens of millions of Americans.

Simulations have played a critical role in the advancement of our knowledge of magnetic reconnection. However, due to the inherently multiscale nature of reconnection, it is impossible to simulate all physics at all scales. For this reason, a wide range of simulation methods have been crafted to study particular aspects and consequences of magnetic reconnection. This article reviews many of these methods, laying out critical assumptions, numerical techniques, and giving examples of scientific results. Plasma models described include magnetohydrodynamics (MHD), Hall MHD, Hybrid, kinetic particle-in-cell (PIC), kinetic Vlasov, Fluid models with embedded PIC, Fluid models with direct feedback from energetic populations, and the Rice Convection Model (RCM).

The Heliophysics Big Year was an extended year where major solar events engaged the public. It included two eclipses (annular on October 14, 2023 and total on April 8, 2024), plus solar max and the Parker Solar Probe perihelion December 24, 2024. After the eclipse of 2017, many millions more Americans planned to view the solar corona. We expanded our eclipse website with activities, citizen science projects, resources, training videos, equipment, and external links. We were the Southwest Regional Coordinator for Citizen CATE 2024 project, training the state coordinators and their teams with the equipment and procedures. We trained teachers at local, regional, national, and international workshops, providing eclipse viewing cards, lenses to make solar cup projectors, a safe viewing screen pattern, and access to the training materials. We made presentations to the media and hosted public events to demonstrate safe eclipse viewing techniques. HMNS hosted live viewing for the annular and total plus solstice and equinox events, reaching tens of thousands of people. HMNS also secured a grant to provide 100 eclipse viewing cards for every public school (8,800+) in Texas. We distributed another 57,000 eclipse viewers to teachers and the public. We appeared in media both in advance of the eclipses and as live commentators. The most lasting and impactful product was our planetarium show Totality, which was given away free and shown in various formats (flatscreen, fisheye, or prewarped). Over 180,000 views of the show and its animations have been documented. We continued to improve our space weather forecasting site, which correctly predicted the major solar storms of May 10-11 and October 8-10, 2024. In total, we reached nearly two million learners.

Recent multi-point measurements, in particular from the Magnetospheric Multiscale (MMS) spacecraft, have advanced the understanding of micro-scale aspects of magnetic reconnection. In addition, the MMS mission, as part of the Heliospheric System Observatory, combined with recent advances in global magnetospheric modeling, have furthered the understanding of meso- and global-scale structure and consequences of reconnection. Magnetic reconnection at the dayside magnetopause and in the magnetotail are the drivers of the global Dungey cycle, a classical picture of global magnetospheric circulation. Some recent advances in the global structure and consequences of reconnection that are addressed here include a detailed understanding of the location and steadiness of reconnection at the dayside magnetopause, the importance of multiple plasma sources in the global circulation, and reconnection consequences in the magnetotail. These advances notwithstanding, there are important questions about global reconnection that remain. These questions focus on how multiple reconnection and reconnection variability fit into and complicate the Dungey Cycle picture of global magnetospheric circulation.

There is ample evidence for magnetic reconnection in the solar system, but it is a nontrivial task to visualize, to determine the proper approaches and frames to study, and in turn to elucidate the physical processes at work in reconnection regions from in-situ measurements of plasma particles and electromagnetic fields. Here an overview is given of a variety of single- and multi-spacecraft data analysis techniques that are key to revealing the context of in-situ observations of magnetic reconnection in space and for detecting and analyzing the diffusion regions where ions and/or electrons are demagnetized. We focus on recent advances in the era of the Magnetospheric Multiscale mission, which has made electron-scale, multi-point measurements of magnetic reconnection in and around Earth's magnetosphere.

This paper aims to quantify the magnetospheric magnetic flux contents under moderate to intense space weather conditions using global simulations. This study is a companion to Akhavan-Tafti, Atilaw, et al. (2023, ) where magnetic flux evolution is presented for a catalog of storm events, using Heliophysics System Observatory (HSO) observations. For this study, we used the Space Weather Modeling Framework (SWMF) in Geospace configuration to study magnetic flux dynamics for a subset of their storm events (15 events). Simulations reliably resolve the storm-time magnetic flux Bz and current density |J| asymmetries across the different storm phases. It is revealed that: relative to the quiet period, flux content is enhanced during the storm sudden commencement (SSC) phase in the dayside by Delta Bz/Bz, quiet = +17%, and reduced in the nightside magnetosphere (r[R-E] < -6 R-E) by -15%. At the same time, the cross-tail current is found to enhance (|J| = 2 nA/m(2)), which suggests the storm impact in the nightside magnetosphere is much earlier in the storm cycle than previously shown. Concurring with previous studies, a significant depletion of magnetic flux by up to -40%, with day-night and dawn-dusk asymmetries, can be seen during the main and recovery phases. This corresponds to the enhanced current density (|J| = 5-8 nA/m(2)) at similar to 6 R-E further confirming the role of ring current in driving magnetospheric dynamics during the main and recovery phases. This is in contrast with the SSC phase wherein the Chapman-Ferraro and cross-tail currents are the dominant current systems.

Various physical processes in association with magnetic reconnection occur over multiple scales from the microscopic to macroscopic scale lengths. This paper reviews multi-scale and cross-scale aspects of magnetic reconnection revealed in the near-Earth space beyond the general global-scale features and magnetospheric circulation organized by the Dungey Cycle. Significant and novel advancements recently reported, in particular, since the launch of the Magnetospheric Multi-scale mission (MMS), are highlighted being categorized into different locations with different magnetic topologies. These potentially paradigm-shifting findings include shock and foreshock transient driven reconnection, magnetosheath turbulent reconnection, flow shear driven reconnection, multiple X-line structures generated in the dayside/flankside/nightside magnetospheric current sheets, development and evolution of reconnection-driven structures such as flux transfer events, flux ropes, and dipolarization fronts, and their interactions with ambient plasmas. The paper emphasizes key aspects of kinetic processes leading to multi-scale structures and bringing large-scale impacts of magnetic reconnection as discovered in the geospace environment. These key features can be relevant and applicable to understanding other heliospheric and astrophysical systems.

We analyze the local dynamics of magnetotail reconnection onset using Magnetospheric Multiscale (MMS) data. In conjunction with MMS, the macroscopic dynamics of this event were captured by a number of other ground and space‐based observatories, as is reported in a companion paper. We find that the local dynamics of the onset were characterized by the rapid thinning of the cross‐tail current sheet below the ion inertial scale, accompanied by the growth of flapping waves and the subsequent onset of electron tearing. Multiple kinetic‐scale magnetic islands were detected coincident with the growth of an initially sub‐Alfvénic, demagnetized tailward ion exhaust. The onset and rapid enhancement of parallel electron inflow at the exhaust boundary was a remote signature of the intensification of reconnection Earthward of the spacecraft. Two secondary reconnection sites are found embedded within the exhaust from a primary X‐line. The primary X‐line was designated as such on the basis that (a) while multiple jet reversals were observed in the current sheet, only one reversal of the electron inflow was observed at the high‐latitude exhaust boundary, (b) the reconnection electric field was roughly five times larger at the primary X‐line than the secondary X‐lines, and (c) energetic electron fluxes increased and transitioned from anti‐field‐aligned to isotropic during the primary X‐line crossing, indicating a change in magnetic topology. The results are consistent with the idea that a primary X‐line mediates the reconnection of lobe magnetic field lines and accelerates electrons more efficiently than its secondary X‐line counterparts.

We analyze a magnetotail reconnection onset event on 3 July 2017 that was observed under otherwise quiescent magnetospheric conditions by a fortuitous conjunction of six space and ground-based observatories. The study investigates the large-scale coupling of the solar wind - magnetosphere system that precipitated the onset of the magnetotail reconnection, focusing on the processes that thinned and stretched the cross-tail current layer in the absence of significant flux loading during a two-hour-long preconditioning phase. It is demonstrated with data in the (1) upstream solar wind, (2) at the low-latitude magnetopause, (3) in the high-latitude polar cap, and (4) in the magnetotail that the typical picture of solar wind-driven current sheet thinning via flux loading does not appear relevant for this particular event. We find that the current sheet thinning was, instead, initiated by a transient solar wind pressure pulse and that the current sheet thinning continued even as the magnetotail and solar wind pressures decreased. We suggest that field line curvature induced scattering (observed by Magnetospheric Multiscale (MMS)) and precipitation (observed by Defense Meteorological Satellite Program (DMSP)) of high-energy thermal protons may have evacuated plasma sheet thermal energy, which may require a thinning of the plasma sheet to preserve pressure equilibrium with the solar wind.

During a storm‐time interval around winter solstice, observations by the Magnetospheric Multi‐Scale (MMS) Mission show multiple distinct magnetopause boundary layers (BLs) in the vicinity of the southern cusp. The microphysics of the solar wind‐magnetosphere interaction during storm times are not well understood, because the observations are relatively lacking. This event enables the opportunity to probe the storm‐time magnetopause, and observations support that MMS was near a reconnection site equatorward of the southern cusp, suggesting active reconnection in close proximity to closed magnetic flux regions in the BL. The Grid Agnostic magnetohydrodynamics (MHD) for Extended Research Applications global MHD simulation shows evidence for transient secondary reconnection sites near the southern cusp, demonstrating mechanisms to form closed field line regions of the BL.

On December 4, 2017 at approximately 6:15:38 UTC, magnetospheric multiscale (MMS) encountered a reconnecting current sheet near the dayside magnetopause. MMS2 passed through the current sheet just sunward of the southward-moving x-line and observed the crescent-shaped electron velocity distributions associated with reconnection. Additionally, MMS2 observed anti-correlated oscillations in the Hall electric field EN and in the parallel electric field Eǁ at a frequency just below the lower hybrid (LH) frequency. These oscillations appear to be LH drift waves (also called corrugations), which have previously been observed along the dayside magnetopause but were not seen to cause the same kinds of oscillations in the electric field components as observed in this event. It appears that MMS2 periodically crosses a separatrix between the region where EN dominates and a different region where Eǁ dominates at the wave frequency likely due to the wave motion. We also observe energy conversion dominated by Eǁ and veǁ, mostly in the L-direction, in this region as opposed to the reconnection electric field EM and meandering electrons moving in the M-direction as is typically observed during reconnection near an x-line.

Texas will be uniquely situated as the nexus of the “X” where the annular eclipse of October 14, 2023 and the total solar eclipse of April 8, 2024 cross. Everyone in the state of Texas will experience at least 84% solar coverage for one or both of these remarkable events, and over 8 million people will be within a 30 minute drive of totality, not counting the dramatic influx of visitors expected because of the favorable weather conditions. Texas is the fastest growing state, and one with the highest fraction (25%) of children under 18. In addition, it is one with a large population of ESL learners in the path of the dark skies. Our goals are three: 1. To bring information to all regions of the state so that every person has a safe experience of a partial and/or annular eclipse; 2. To maximize the number of Texans (residents and visitors) who can experience totality; and 3. To create a set of activities for schools, for groups, and for citizen scientists to collect data on the environment and on bird and animal behavior during these events. We have created two websites for information about the upcoming eclipses http://space.rice.edu/eclipse and http://texaseclipse.net; we have a mailing list for people and educators interested in eclipses http://eepurl.com/cv68Qj and we have seven eclipse animations already created for planetariums and schools: https://space.rice.edu/eclipse/eclipse_animations.html, plus a number of diagrams. We are creating two more animations describing annular eclipses which should be ready for the AGU meeting. We have developed a set of Powerpoint slides and animations to be used for eclipse training, and special “dome versions” using the fulldome animations, to be used in fixed and portable planetariums. We have already done trainings in South Texas (where the eclipses cross) and will work with AAS, NASA, and other groups to ensure the widest possible dissemination of eclipse information, particularly safety information. By the time of AGU we will have already used these materials in teacher trainings at the CAST conference and planetarium trainings for LIPS, and will post them for download. Educational and safety materials will be provided in both English and Spanish, and presentations for both flatscreen Powerpoint or fulldome planetarium programs will be made freely available, thanks to the NASA HEAT program.

We analyze data returned by the Magnetospheric Multiscale mission (MMS) constellation during a rapid (∼1.5 s) traversal of a flapping and reconnecting current sheet (CS) in the near‐Earth magnetotail (X ∼−20 R E ). The CS was highly tilted, with its normal pointing strongly duskward. Its extreme thinness was confirmed by a curvature analysis of the magnetic field lines. The event was associated with a guide field of 8% of the reconnecting components. From the pitch angle distributions of low‐energy electrons we infer a crossing earthward of the X‐line. Traveling practically normal to the CS, MMS encountered an ion diffusion region (IDR) in which was embedded an electron diffusion region (EDR). IDR signatures included breaking of the ion frozen‐in condition in the presence of Hall B and E fields. EDR signatures included a strong out‐of‐plane current associated with a superAlfvénic electron jet, positive energy transfer, and a temperature anisotropy ( Te ∥ > Te ⊥ ) which disappeared at the field reversal. Derived scale sizes normal to the CS are: ∼6.9 d e (EDR) and ∼0.4 d i (IDR; 40 and 100 km). We estimate the average dimensionless reconnection rate as 0.077 ± 0.050. The observations and inferences are supported by particle‐in‐cell (PIC) numerical simulations. We find very good agreement in the reconnection rates. We also discuss the effects of asymmetries in the density, temperature and magnetic field strength on the Hall fields and length of the outflow jets. The event is associated with a substorm onset which began 7 min after the MMS observations.

On 8 September 2018, at nearly 14:51:30 UT, the Magnetospheric Multiscale (MMS) spacecraft encountered an electron diffusion region near the center of a flux-rope type dipolarization front. The observed signature of the magnetic field in geocentric solar ecliptic included a bipolar B-z coinciding with a peak in B-y and vertical bar B vertical bar as is typical for a flux rope. At the same time, all three spacecraft with available plasma data observed a decrease in density and an increase in temperature over ion scales near the reversal in B-z. These ion-scale changes are expected in a dipolarization front. The three spacecraft with available electron plasma data also observed clear evidence of electron-scale reconnection just after the B-z reversal including ideal magnetohydrodynamics violation, a large out-of-plane current, a large j . E' energy conversion, and crescent-shaped electron velocity distributions. This is the first time reconnection has been observed near the center of a flux rope on an electron-scale during such an event, and MMS was likely very close to the reconnection X-line.

Space weather forecasting is a coordinated attempt that takes data from ground- and space-based instruments and combines them with science-based numerical models to generate accurate and uninterrupted forecasts of the variable conditions in the near-Earth space environment, particularly geomagnetic storms and auroral activity. It includes issuing short-term forecasts through event-driven (e.g., solar flares, geomagnetic storms, proton events, electron events) alerts and warnings, offering daily forecasts of solar and geomagnetic activity and other long-term forecasts and warnings. Space weather research can be viewed as a cross-disciplinary scientific effort, or as a hybrid of basic space science research and applied science. Forecasters come from government, academic, or private sectors, and forecast models exist to predict actual physical parameters (or their proxies) and to predict the rate of changes over a specific time range. They provide advanced prediction, over a variety of parameters, of the state of the regions within close proximity of the Earth and of the region between the Sun and Earth, with alerts and warnings issued periodically that could extend out to the order of minutes to days, depending upon the object of forecast. They rely on real-time, in situ data measurements to augment the process of decision making. The level of confidence a forecaster places on predictive tools is critical for a user (e.g., power company, airline industry) to invest resources where such tools should be updated and augmented through improved understanding as needed, minimize false alarms, and offer better reliability and redundancy at critical times.

We have used the high-resolution data of the Magnetospheric Multiscale (MMS) mission dayside phase to identify twenty-one previously unreported encounters with the electron diffusion region (EDR), as evidenced by electron agyrotropy, ion jet reversals, and j dot E greater than 0. Three of the new EDR encounters, which occurred within a one-minute-long interval on November 23rd, 2016, are analyzed in detail. These events, which resulted from a relatively low and oscillating magnetopause velocity, contained large electric fields (several tens to hundreds of milliVolts per meter), crescent-shaped electron velocity phase space densities, large currents (greater than 2 microAmperes per square meter), and Ohmic heating of the plasma (near or exceeding 10 nanoWatts per cubic meter). Because of the slow in-and-out motion of the magnetopause, two of these events show the unprecedented mixture of perpendicular and parallel crescents, indicating the first breaking and reconnecting of solar wind and magnetospheric field lines. An extended list of thirty-two EDR or near-EDR events is also included, and demonstrates a wide variety of observed plasma behavior inside and surrounding the reconnection site.