Helios is the ancient Greek god of the Sun, but the name appears across science, medicine, and space exploration. Depending on what brought you here, Helios could refer to a deity who drove his golden chariot across the sky each day, a protein that keeps your immune system in check, a pair of NASA solar probes that once held the speed record for fastest human-made object, or a laser used in dermatology. Here’s what each one does.
Helios in Greek Mythology
In ancient Greek religion, Helios personified the Sun itself. His primary job was driving a golden chariot pulled by four white horses from east to west across the sky every day, rising from the river Oceanus at dawn and descending beneath the earth at dusk. The goddesses of the seasons helped him yoke his horses each morning. He was typically depicted as a handsome, beardless young man crowned with a shining aureole of twelve rays, one for each month of the year.
Beyond lighting the world, Helios served as an all-seeing witness. Because his light touched everything, the Greeks believed nothing escaped his notice, which made him the god people invoked when swearing oaths. He was also considered a god of sight, life, and creation. One tradition held that he helped form animals from primeval mud.
His most famous stories come from Homer’s Odyssey. On the island of Thrinacia, Odysseus’s crew slaughtered Helios’s sacred cattle despite warnings not to. Helios demanded Zeus punish them, and Zeus struck their ship with a thunderbolt, killing every man except Odysseus, who hadn’t touched the cattle. In another well-known myth, Helios caught Aphrodite and Ares in an affair and immediately reported it to Aphrodite’s husband, Hephaestus. He also witnessed Hades kidnapping Persephone when no other god noticed, and in one story he restored the blinded hunter Orion’s eyesight. His major cult center was on the island of Rhodes, where the famous Colossus of Rhodes was built in his honor. Sacred animals associated with him include horses, roosters, wolves, and cattle, and the poplar tree was considered his because of the sun-like shimmer of its leaves.
Helios Protein and the Immune System
In biology, Helios refers to a protein encoded by a gene called IKZF2, located on chromosome 2 in humans. Its most important job is stabilizing a type of immune cell called a regulatory T cell. These cells act as peacekeepers: they prevent your immune system from attacking your own body. Helios helps lock regulatory T cells into their suppressive state so they keep doing that job reliably.
It works by recruiting a molecular complex that remodels how DNA is packaged inside the cell, effectively turning down the volume on certain immune signals. For example, it dampens the production of a key immune-stimulating molecule called IL-2 and its receptor, which helps keep immune responses from spiraling out of control.
When Helios expression is lost, things go wrong. The body can develop autoimmune problems, particularly affecting a process called the germinal center reaction, where immune cells mature and produce antibodies. Without proper Helios function, this can lead to either too few antibodies (leaving you vulnerable to infection) or B cells that mistakenly target your own tissues.
Helios also shows up in cancer research. In tumors, it’s found primarily in a subset of CD4+ T cells that infiltrate the tumor, with very little expression in CD8+ T cells (the ones that directly kill cancer cells). Researchers are studying whether Helios levels in tumor-infiltrating immune cells can help predict survival outcomes, particularly in cancers like advanced gastric cancer. Its presence is closely tied to regulatory T cells inside tumors, which can sometimes suppress the very immune response needed to fight the cancer.
NASA’s Helios Solar Probes
Helios 1 and Helios 2 were a pair of joint German-American space probes launched in the 1970s to study the Sun up close. Their mission was to investigate solar wind, magnetic and electric fields, cosmic rays, and cosmic dust in the region between Earth’s orbit and roughly 0.3 astronomical units from the Sun (about 29 million miles).
Helios 1 made its closest pass on March 15, 1975, flying within 29 million miles of the Sun at 148,000 miles per hour. At the time, it was the closest any human-made object had ever gotten to our star. Among its findings: there are 15 times more micrometeorites near the Sun than near Earth. Helios 2 followed in April 1976 and set its own records, reaching a speed of about 153,454 miles per hour, making it the fastest human-made object relative to the Sun for over four decades. That record held until NASA’s Parker Solar Probe surpassed it in 2018, eventually reaching speeds above 430,000 miles per hour.
Helios Laser in Dermatology
The Helios III is a Q-switched Nd:YAG laser used in skin clinics for pigment-related treatments. It fires extremely short pulses of light at specific wavelengths that shatter pigment particles in the skin without causing significant heat damage to surrounding tissue. The laser operates at multiple wavelengths, allowing it to target pigment at different depths.
Its primary uses include tattoo removal across various ink colors, treatment of pigmented lesions like melasma, freckles, and age spots, and addressing post-inflammatory hyperpigmentation (the dark marks left after acne or injury). It’s also used for skin rejuvenation, evening out skin tone and texture, carbon peels, and lip rejuvenation. A feature called Real Twin Pulse technology fires two closely spaced pulses that penetrate deeper into the skin while minimizing thermal damage.
Helios in Solar Energy and Lighting
In renewable energy, the Helios name is used for the QULON HELIOS, a solar power management module designed for off-grid street lighting systems. It charges batteries from solar panels during the day and powers LED lights at night. The module uses maximum power point tracking technology at 97% efficiency and manages a three-step battery charging process. It supports remote monitoring and control over cellular networks, letting operators manage entire lighting networks without visiting each unit. It works across a temperature range of negative 40 to 70 degrees Celsius, making it suitable for extreme climates.