What the Sun Means in Astrology

The Sun is the central luminary of our solar system, the only star in our system, and the source of all biological life on Earth. Astronomically it's a ball of plasma about 1.4 million kilometers across, with a core temperature near 15 million degrees.

In astrology the Sun inherits its astronomical role. It's the core of the chart, the main "planet" (formally a star, but in astrology traditionally counted as a planet — like the Moon) around which all other parts of the personality orbit.

In plain terms: the Sun in your chart is "who I am" at the most basic level. Not "what I do," not "how I feel," not "how I talk" — but who you are in essence. It's the center of your identity.

Key functions of the Sun:

• Will and decision-making. Where you make conscious choices and where your inner direction lights up.
• Life force. How much natural energy you have, how you spend it, and what warms you.
• Self-expression. How you show yourself to the world — creativity, leadership, charisma.
• Ego and identity. Who you are to yourself and how you name yourself internally.
• The father archetype. In a woman's chart the Sun is the "inner father" and the type of "significant men" in her life. In a man's chart it's the image of his own "I-as-man."

The Sun moves through the whole zodiac in a year, spending about a month in each sign. That's why the Sun sign is the most "mass-produced" parameter of the chart — you share it with thousands of people born in the same month. Individuality comes through the house and aspects.

The Mythology of the Sun

In Greek myth Helios is the sun god who drives a fiery chariot across the sky every day. In the Roman tradition he's Sol. In late Hellenism Helios gradually merges with Apollo, god of light, the arts, oracles, and healing. Apollo isn't just "light" but conscious force: reason, beauty, measure, music.

In ancient Egypt the Sun is Ra, supreme god sailing across the sky in a boat. In Babylonian tradition it's Shamash, god of justice (light sees everything, so he's also the judge). For the Aztecs it's Tonatiuh, demanding sacrifices to rise again each morning.

Across all mythologies the Sun is tied to power, order, visibility, and judgment. It's "what illuminates and is seen." In astrology that mythological essence remains: wherever your Sun is in the chart, that's where you're most visible, most "yourself," most active.

Unlike Jupiter (excess, expansion, luck), the Sun is more focused. Jupiter "gives out," the Sun "reveals." Jupiter expands, the Sun shines. Different functions.

The Sun Through the 12 Signs — How You Show Up

The Sun sign tells us through which archetype you reveal yourself. It's the "type of light" you emit.

Sun in Aries

Active, direct, initiating. "I'm first" is the keynote. These people don't like waiting, don't like middlemen, and go straight at things. Natural leaders, sometimes hot-tempered, sometimes impatient. Strength: courage to start from zero. Weakness: impulsiveness that wipes out results.

Sun in Taurus

Calm, grounded, material. "I build" is the keynote. These people are slow but durable. Often a strong body, love of good food, sensuality, attachment to money and beautiful things. Strength: stability, loyalty. Weakness: stubbornness, laziness, reluctance to change.

Sun in Gemini

Curious, flexible, talkative. "I speak" is the keynote. These people are intellectual "switchboards" — they need to constantly exchange information. Often writers, teachers, people in media. Strength: flexibility and connections. Weakness: scattering, superficiality, trouble going deep.

Sun in Cancer

Sensitive, emotional, home-centered. "I care" is the keynote. These people are empathic, attached to family and roots, often good parents. They love cooking and making a home. Strength: emotional depth, maternal instinct (in men — paternal). Weakness: vulnerability, taking offense, holding on to the past.

Sun in Leo

Bright, demonstrative, regal. "I shine" is the keynote. These people are natural centers of attention — performers, leaders. They love the stage, recognition, grand gestures. Strength: generosity, charisma, ability to lead. Weakness: vanity, constant need for admiration, fragile ego.

Sun in Virgo

Analytical, neat, service-oriented. "I improve" is the keynote. These people are masters of detail, technique, systems. Often doctors, engineers, craftspeople, analysts. Strength: precision, reliability, follow-through. Weakness: criticism of self and others to the point of neurosis, perfectionism.

Sun in Libra

Aesthetic, diplomatic, paired. "I find balance" is the keynote. These people are masters of negotiation, harmony, relationships. Often creative professions, design, law. Strength: seeing both sides, sense of beauty. Weakness: indecision, fear of conflict, dependence on others' approval.

Sun in Scorpio

Deep, passionate, transformative. "I go all the way" is the keynote. These people aren't afraid of dark themes: death, sex, other people's money, crisis. Often financiers, psychologists, doctors, people in the security sector. Strength: inner power, capacity to survive what would break others. Weakness: control, jealousy, destructiveness.

Sun in Sagittarius

Expansive, philosophical, traveling. "I seek truth" is the keynote. These people are natural teachers, missionaries, travelers. Often connected to foreign countries, philosophy, law, higher education. Strength: optimism, a broad mind, the ability to inspire. Weakness: moralizing, "I know how it should be," escapism.

Sun in Capricorn

Serious, disciplined, status-oriented. "I build for the long term" is the keynote. These people are natural architects of reality. They love structure, responsibility, recognition through achievement. Often executives, politicians, businesspeople. Strength: discipline, reliability, ability to wait. Weakness: cynicism, workaholism, emotional dryness.

Sun in Aquarius

Unconventional, progressive, communal. "I change the system" is the keynote. These people are natural innovators, geniuses, and oddballs. Often connected to technology, science, social projects. Strength: originality, friendliness, ability to see the future. Weakness: detachment, ungrounded ideas, emotional coolness.

Sun in Pisces

Sensitive, artistic, spiritual. "I dissolve" is the keynote. These people are natural artists, mystics, helpers. Often connected to art, medicine, psychotherapy, spiritual practice. Strength: empathy, intuition, the ability to sense the invisible. Weakness: blurred boundaries, addictive tendencies, martyrdom.

The Sun Through the 12 Houses — Where You Are Most "You"

If the sign is how you shine, the house is where. It's the area of life where you're most active, most expressed, where the "main event" of your life happens.

Sun in the 1st House

Personality up front. You're visible, recognizable, your individuality is your main tool. Often a striking appearance, a memorable face. Leadership and visibility come naturally. Life is often built "through yourself" — as a personal brand, an authority, a strong "I." A good house for people for whom being themselves matters most.

Sun in the 2nd House

The realm of money and material values. The theme of your own income, your possessions, your body is central. Often a good relationship with money, the ability to earn through personal talents. Sometimes — overblown attachment to the material. The body is in focus too: either well cared for or problematic.

Sun in the 3rd House

The realm of communication, learning, and the immediate circle. Life is filled with conversations, messages, short trips. Often journalists, writers, school-level teachers, salespeople. Sibling relationships matter. Love of information, flexibility, versatility.

Sun in the 4th House

The realm of home and family. Life often revolves around family: parents, children, home, roots. A strong attachment to place, sometimes a family business or hereditary profession. Late blooming (the 4th house is "roots," so things often open up after 35–40). For men, the figure of the mother carries special weight.

Sun in the 5th House

The realm of creativity, children, romance. Life is rich in self-expression, play, romance. Often creative professions (actors, painters, musicians), or a strong love of children. Romantic stories are an important part of life, sometimes several memorable affairs. Love of the stage and of attention.

Sun in the 6th House

The realm of work and health. Life is built through daily labor. Often doctors, craftspeople, analysts, specialists with deep expertise. A love of routine and order. The body is an important theme — often either careful attention to health or its opposite (a tendency to overload). "Work as meaning."

Sun in the 7th House

The realm of partnership. Life often shows up through relationships: marriage, business partners, public connections. Often an early marriage or a defining partnership. Partners are the central backdrop of life. A good house for those who work as a duo or in a team.

Sun in the 8th House

The realm of transformation, other people's resources, crisis. Life often passes through serious crises and rebirths. Often financiers (working with other people's money), psychologists, doctors, people in the security sector. A deep sexual theme. Sometimes inherited stories. Life is intense, not "easy."

Sun in the 9th House

The realm of higher education, travel, worldview. Life is often tied to foreign countries, teaching, philosophy, law. Often emigration, an international career, an academic profession. Love of big ideas and wide horizons.

Sun in the 10th House

The realm of career and status. One of the most "ambitious" houses for the Sun. Life is built through professional recognition. Often public figures, politicians, well-known specialists in their field. A strong will to achieve, sometimes at the cost of personal life.

Sun in the 11th House

The realm of communities and large projects. Life often shows up through collective ventures: social movements, IT projects, teams. Many friends, a wide circle. Often the role of "connector" or "movement leader."

Sun in the 12th House

The realm of solitude and the subconscious. One of the hardest houses for the Sun — the ego "hides" here. Life is often internal: creativity, spiritual practice, psychotherapy, sometimes behind-the-scenes work. Many artists, psychotherapists, mystics. Things open up later and through inner work.

Aspects from the Sun to Other Planets

Aspects — angles between the Sun and other planets — shape the internal conflicts and supports of your personality.

Sun-Moon

This is the core axis: conscious "I" (Sun) and emotional "I" (Moon).

• Conjunction — a fused personality, emotions aligned with will. Sometimes — difficulty separating "what I feel" from "what I want."
• Trine/sextile — harmony between mind and feeling. Easy self-acceptance.
• Square/opposition — internal conflict: will pulls one way, emotions pull the other. Often shows up in people whose parents had a tense relationship in childhood. A strong engine of development.

Sun-Mercury

Mercury never moves more than 28° from the Sun. So only conjunction or a small sector is possible.

• Conjunction — thought and will line up. Often vivid communicators.
• Mercury in the same sign as the Sun but in a different sector — a small distance between "I" and "how I think," which allows for self-reflection.

Sun-Venus

Venus, like Mercury, is always close to the Sun (no more than 48° away). Only conjunction or sextile is possible.

• Conjunction — a harmonious, charming personality; love and creativity are naturally part of the "I."
• Venus in a different sign but nearby — a gentle ability to please and an aesthetic sense.

Sun-Mars

The pairing of "will + action."

• Conjunction — a strong personality, active, sometimes aggressive. "I do."
• Trine/sextile — healthy energy, athleticism, leadership without domination.
• Square/opposition — internal conflict between wanting and acting. Often anger and impatience. A strong engine, once integrated.

Sun-Jupiter

The pairing of "will + expansion."

• Conjunction — a generous, optimistic personality, drawn to big goals. Sometimes — vanity and overestimating possibilities.
• Trine/sextile — natural luck, an easy attitude toward life.
• Square/opposition — conflict between "I" and "too much." Inflated ego, a tendency to overrate oneself.

Sun-Saturn

One of the most "formative" aspects.

• Conjunction — a serious, disciplined personality. Often early responsibility. Sometimes — coldness and a depressed undertone.
• Trine/sextile — natural maturity, the ability to pursue long-term goals.
• Square/opposition — an inner "strict father," the voice that says "you're not good enough." One of the most common aspects in high achievers — because it's a powerful engine that works through resistance.

Sun-Uranus

• Conjunction — an original personality, sometimes "not of this world," prone to sudden decisions.
• Trine/sextile — flexibility, capacity for innovation.
• Square/opposition — instability, rebellion against authority, frequent reversals in life.

Sun-Neptune

• Conjunction — an artistic, sensitive personality, sometimes prone to illusions and addictions.
• Trine/sextile — healthy empathy, artistic flair.
• Square/opposition — trouble with the boundaries of "I," tendency to self-deception, sometimes addiction.

Sun-Pluto

• Conjunction — a powerful, transformative personality. Often passes through serious rebirth crises.
• Trine/sextile — a healthy capacity for deep change.
• Square/opposition — frequent collisions with themes of power and control. Possible crises after which the "I" is fully rebuilt.

Orbs — What Counts as a "Working" Aspect

In practice an aspect is considered "working" if the angle between the planets is precise enough. The allowed deviation is called the orb:

• For conjunction, opposition, square, trine — usually 7–10°.
• For sextile — usually 5–6°.
• For minor aspects (semisextile, quincunx) — 2–3°.

The tighter the aspect, the more strongly it works. Exact conjunctions (1° and under) often produce the sharpest expressions — a "hard" aspect working at its peak.

Sun aspects with an orb under 3° usually produce the most visible personality traits. Aspects with an orb of 7–10° are in the background — they still work, but more softly.

Multiple Aspects

The Sun often has several simultaneous aspects: e.g. a trine to Jupiter + a square to Saturn + a conjunction to Mercury. This isn't a "contradiction" but a complex: different functions running at once, sometimes supporting one another, sometimes in conflict.

With multiple aspects the personality is more complex, multilayered. Simple aspects give a "readable" character; complex stacks give a "multidimensional" one with contradictions.

A Strong vs. Weak Sun — What That Means

In classical astrology each planet has signs of strength and weakness.

Strong Sun

• Rulership — Leo. The Sun in Leo is in its "own" sign and works at full power: bright personality, natural charisma, leadership.
• Exaltation — Aries. The Sun in Aries is in an especially strong position: "new beginning," will, initiative at maximum.

A strong Sun gives:

• Natural self-confidence.
• Easy self-expression.
• A strong will.
• The capacity to lead and to be seen.

It's not a "guarantee of success," but it's a healthy foundation for personal development. People with a strong Sun find it easier to own themselves, make decisions, and not get lost in others' expectations.

Weak Sun

• Detriment — Aquarius. The Sun in Aquarius is "out of its element": the personality often hides behind the collective; individuality comes through being unusual rather than through direct shine.
• Fall — Libra. The Sun in Libra is weakened by the opposite nature of the sign: "I" hides behind "we," behind relationships, behind the search for balance. Often a loss of one's own center to please a partner.

A weak Sun is not a verdict. It just means the function "being yourself" doesn't work automatically — it requires conscious work. Many great people had a weak Sun and compensated through discipline, creativity, or strong other planets.

A weak Sun in a woman's chart often means a "habit of giving the center to others" — to a husband, to children, to parents. Reclaiming the center is part of growing up.

Neutral Sign Positions

In the rest of the signs the Sun is neutral. Not "strong," not "weak." It works as colored by the sign. The Sun in Taurus — slow and material. The Sun in Cancer — emotional and home-centered. The Sun in Sagittarius — expansive and philosophical.

"Strength" and "weakness" are classical concepts and modern psychological astrology often re-examines them. Many practitioners prefer to say "distinctive" or "in need of work" rather than "weak."

A Retrograde Sun — Can That Happen?

Technically — no. From Earth's point of view the Sun never moves retrograde: its "motion" along the ecliptic is a reflection of Earth's motion around it. So in any natal chart the Sun is always direct.

Sometimes people ask about a "retrograde Sun" — they're confusing it with eclipses. If your birth fell at or near a solar eclipse, that's sometimes read as a "Sun under eclipse," which in some schools is interpreted as a weakened Sun. That's a different phenomenon, not retrograde motion.

The Sun in a Woman's vs. a Man's Chart

The basic meaning of the Sun is the same for everyone: core of personality, will, identity. But there are nuances in social expression and psychology.

For Men

The Sun in a man's chart is the man himself, his "I-as-man." A strong Sun (in Leo, Aries, in the 1st or 10th house, with harmonious aspects) is a "supportive man" — confident, realizing himself through will and achievement.

A weak or afflicted Sun (in Libra — fall, with tense aspects to Saturn or Neptune) — inner uncertainty in the "I" role, often compensated by external toughness or, conversely, by passivity.

In a man's chart the Sun is also tied to the theme of the father and his own fatherhood.

For Women

In a woman's chart the Sun has a double meaning:

1. Her own "I" and will — same as for a man.
2. The "inner father" and the type of "significant men" — her relationship with authority, the father archetype, the type of man she recognizes as "the main one."

This often shows up in partner choice. A woman with the Sun in Capricorn often chooses older, high-status partners. With the Sun in Leo — bright, charismatic ones. With the Sun in Cancer — caring, home-loving ones.

If a woman's Sun is in a tense aspect to Saturn, there's often a complicated history with her actual father behind it. That theme often replays in adult relationships through choosing "cold, rejecting" partners — until it's worked through in therapy.

The Sun on the Angles of the Chart — Where the Core Points

The "angles" of the natal chart are the four main points: the Ascendant (east, 1st house), the MC (south, 10th house), the Descendant (west, 7th house), and the IC (north, 4th house). When the Sun sits close to one of these points (within 5–8°), it works especially strongly.

Sun on the Ascendant

The brightest, most visible personality. Appearance and character match — you are what you seem. Often public figures, leaders, performers, charismatics. Sometimes a swollen ego.

Sun on the MC (Midheaven, 10th House)

Career and public status are central. Often fame, professional success, social recognition. A strong Sun on the MC is a classic marker of a "leader" or well-known specialist.

Sun on the Descendant (7th House)

The "I" expresses itself through the partner. Life is largely built through relationships and significant others. Often striking, visible partners. Sometimes a dissolving into partnership.

Sun on the IC (4th House)

The "I" points inward, into the home, into the roots. The personality unfolds through family, through home, through private space. Often late blooming, a "second wind" after 40 once there's a stable home.

The Sun on an angle is an amplification of the solar function. If your Sun is near one of the angles, read this theme carefully — it often becomes central to your life.

The Sun in Synastry

In two-person compatibility the Sun plays a special role.

• One person's Sun conjunct or in harmony with the other's Moon — the classic "kindred soul." One shines, the other warms. More in our article on compatibility.
• One person's Sun conjunct the other's Sun — two identical archetypes. Possible strong recognition, but sometimes competition.
• One Sun square the other Sun — an "I-vs-I" conflict, often attraction through tension.
• One person's Sun in a significant house of the other — the "I" lands in an important area of the partner's life. If the husband's Sun is in the wife's 4th house, he becomes the center of her home. If in the 10th, the center of her career. This shapes the role in the pair.
• The Sun in synastry with the lunar nodes — a karmic meeting, especially involving the north node.

Which Planets Influence the Sun Most

In a natal chart every planet interacts with the Sun in some way, but not all carry the same weight. The most influential are:

• The Moon. If the Sun is "I-as-mind," the Moon is "I-as-feeling." Their pairing decides how whole you are or how internally divided. The core axis of the personality.
• Saturn. The most "structuring" planet. An aspect from Saturn to the Sun is the "father" story, the theme of discipline, limitation, authority. One of the key factors in maturity.
• Jupiter. "Expands" the Sun. A harmonious Jupiter gives confidence, optimism, scope. An overloaded one gives vanity and overestimation.
• Pluto. Deep transformation. Pluto-to-Sun aspects often mean serious rebirth crises of the personality — sometimes several in a lifetime.

These four pairings are often called "formative" for the Sun. Mercury, Venus, and Mars "outfit" the Sun from outside (how you speak, love, act). Uranus and Neptune add either originality or dissolution.

Cycles of the Sun — Solar Returns

The Sun returns to its natal position about once a year — around your birthday. This is called the Solar Return.

What a Solar Return Is

At the moment the transiting Sun returns to the exact degree and minute it occupied at your birth, a new chart is cast for that moment. This chart is the chart of your year. It describes:

• The main themes of the coming year.
• Which house the Solar Return Sun lands in — the area of life that will be in focus.
• Which aspects activate — what will come easier and what harder.

The Solar Return is active roughly from one birthday to the next. It's one of the main tools of annual forecasting.

Key Points of the Solar Return

• The house of the Solar Return Sun — the central area of the year. If it lands in the 7th house — a year of partnership. In the 10th — a year of career. In the 4th — a year of home and family.
• The Solar Return Ascendant — the main "tone" of the year. An Aries ASC — an active year; Pisces — a sensitive one.
• The ruler of the Solar Return Ascendant — wherever it sits describes "where you'll be carried" this year.
• Aspects in the Solar Return — harmonious ones give ease, tense ones give growth through resistance.

Relocated Solar Return and Birthday Travel

Because the Solar Return is cast for the specific geographic location where you spend your birthday, modern astrology has a practice of "relocated Solar Returns": travel on your birthday to a city where the Solar Return will be more favorable.

This is a specialized technique, and its effectiveness is debated. Most serious astrologers think the year's main themes are set by slow transits to the natal chart, not by tying the Solar Return to a place.

Intermediate Points of the Solar Cycle

Within the yearly cycle there are intermediate points where the transiting Sun forms a square or opposition to its natal position:

• Rising square (three months after the birthday) — the first test of the year.
• Opposition (six months after) — the peak of the year, a check on plans.
• Setting square (nine months after) — closing out the old.
• Return (the birthday) — a new cycle.

These points often line up with real-life events, especially if slow transits of Jupiter, Saturn, or Uranus are layered on top.

The Sun and the Ascendant — Two Different Faces

Working with the Sun often raises the question: "I have the Sun in Virgo and the Ascendant in Leo — who am I, then?"

These are two different layers of the personality:

• The Ascendant is the mask, the way you present. How you show up, how you dress, the first impression you make. The "shell."
• The Sun is the core, who you are inside. What drives you at the deep level.

In the example "Sun in Virgo, Ascendant in Leo": you present like a Leo — bright, visible, charismatic. But inside you're Virgo — analytical, attentive to detail, in love with order and quality. That's a workable combination: vivid outer presentation + precise inner work.

Often strong specialists are people whose Ascendant and Sun "do the same job": e.g. Ascendant in Aries (active presentation) + Sun in Sagittarius (expansion) — a natural leader and teacher.

When the Ascendant and Sun "clash" (e.g. Ascendant in Cancer — soft presentation; Sun in Aries — sharp core), it often produces the feeling "I'm not who I seem to be." Externally the person seems quiet; inside they're a fighter. The work is to learn to sync both layers.

More on the Ascendant — in our article.

How to "Light Up" Your Sun

This is the practical part. Many people come in with "things are okay, but I feel like I'm not in my place" — and behind that often sits a suppressed Sun: you're living not from your core but from others' expectations.

A few principles:

1. Know your solar script. If your Sun is in Virgo, don't try to live like a Leo. If your Sun is in Sagittarius, don't try to live like a Capricorn. Basic, but many people ignore it: they try to "be" not their archetype.
2. Give the solar area its place. The house your Sun sits in is the area where you're most "you." Don't squash it. Sun in the 5th — you need creativity and romance. In the 10th — career. In the 4th — home and family. Ignoring that drains your energy.
3. Work with the aspects. A Sun square Saturn or Pluto isn't a "curse" but a field for work. Mastery grows through that resistance. It atrophies through avoidance.
4. Accept your visibility. The Sun is always being seen. Many people with a strong Sun (1st, 5th, 10th houses) are afraid of being visible because they were "punished" for it in childhood. Reclaiming the right to shine is part of Sun work.
5. Distinguish Sun from Ascendant. These are different layers: the Ascendant is the mask, how you present; the Sun is who you are inside. More — in our article on the Ascendant.

Common Mistakes in Working with the Sun

• Assuming "the Sun sign is everything." This is the biggest myth of pop astrology. The Sun sign is one of ten parameters and gives only a rough outline by itself. A full chart is a stack of ten planets, houses, and aspects.
• Ignoring the house of the Sun. Many read only the sign, but the house is often more important for understanding "where your life is happening."
• Treating a "weak" Sun as a defect. A Sun in Libra or Aquarius is "formally weaker," but it doesn't make the personality worse. Each sign gives its own type of light.
• Substituting the Moon for the Sun. The Moon is the emotional sphere, the Sun is the will. If you live "from the Moon," following feelings without will, your Sun atrophies. Both functions are needed.
• Being afraid to be seen. Many people with a strong Sun avoid visibility out of fear of criticism. That suppresses the core.

FAQ

Frequently asked

How is the sun sign different from the Sun in the natal chart?

"Sun sign" is shorthand for "the sign your Sun sits in." In pop astrology (magazine horoscopes) it's the only parameter people check. In a full natal chart the Sun gives three dimensions: sign (type of light), house (area of life), aspects (internal conflicts and supports). The full picture is dozens of times more informative than just the sun sign.

Which matters more — the Sun's sign or its house?

They give different information. The sign is how you shine, your archetype. The house is where — the area of life where you're most "you." Understanding personality takes both. For "where the main action of your life is happening" the house is often more important. For "what you're like inside" — the sign.

Can the Sun be retrograde in a natal chart?

Technically — no. From Earth's vantage point the Sun never moves retrograde, because we move around it, not the other way around. So in any chart the Sun is always direct. Sometimes "retrograde Sun" gets confused with being born during a solar eclipse — a different phenomenon describing a weakened Sun.

What does it mean to have the Sun in the 12th house?

It's one of the most "internal" houses for the Sun. Life often happens "behind the scenes": creativity, spiritual practice, psychotherapy, sometimes service in closed institutions (hospitals, monasteries). Things open up later, through inner work. Not a "weak" life, but a different one — deep, not public. Many artists, mystics, and psychotherapists have a 12th-house Sun.

How is the Sun connected to the father?

In classical astrology the Sun is the "father archetype": the model of the masculine, authority, the figure of the "significant man." In a man's chart this often shows up as the image of his own masculinity. In a woman's chart — as the type of partner she recognizes as "hers" and her relationship with her actual father. Sun-Saturn aspects are often read as "the father story," harmonious or conflicted.

What does a Saturn square to the Sun mean?

One of the most "formative" aspects. An inner voice of "you're not good enough," early responsibility, seriousness from childhood. Often a cold or demanding father stands behind it. On the downside — depressive episodes and low self-worth. On the upside — a powerful engine of achievement: many major executives and entrepreneurs have exactly this aspect.

Can you 'strengthen' your Sun?

Not in a magical sense, but in a practical one — yes. Working with the Sun is owning your core and living from it. Know your sun sign and house, give the solar area its space (Sun in the 5th — you need creativity; in the 10th — career), work with the aspects through resistance, don't run from your visibility. That's the "strengthening" — through awareness, not rituals.